How to Install a Combination Boiler/Water Heater | Ask This Old House

This Old House plumbing and heating expert Richard Trethewey replaces a water heater and boiler with a single unit that's much more efficient. (See below for a shopping list, tools, and steps.)
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Richard replaces an old water heater and heating boiler with a single unit that is much more efficient.
Shopping List for How to Install a Combination Boiler/Water Heater:
Plywood panel, used for mounting new combination boiler[BR]
Combination boiler/water heater, including mounting hardware
PVC pipe and fittings
Outdoor temperature sensor
PVC condensate line with limestone neutralizer
Condensate pump
Tools List for How to Install a Combination Boiler/Water Heater:
Screwdriver
Drill/driver with 4-inch hole saw
Tape measure
Steps for How to Install a Combination Boiler/Water Heater:
1. Mount a plywood panel to the basement wall to serve as a mounting panel for the new combination boiler.
2. Run new gas, electrical, and plumbing lines to the plywood panel.
3. Screw the metal mounting brackets to the plywood panel, then hang the combination heater onto the brackets.
4. Drill two 4-inch-diameter holes through the house wall for the exhaust vent and air intake vent. Be sure the air intake is above the snow line, and that the exhaust vent is 12 inches from a window and 12 inches from the air intake.
5. Use PVC pipe and fittings to create the exhaust and air intake vents. Run the piping from the boiler through the exterior wall.
6. Connect hot- and cold-water lines to the combination boiler to deliver water to the heating system and the domestic water fixtures.
7. Connect the gas line and new electrical cable to the combination boiler.
8. Mount an outdoor temperature sensor onto the north side of the house to help regulate the production of hot water.
9. Run a PVC condensate line with limestone neutralizer from the combination heater to a nearby utility sink drain or floor drain. Use a condensate pump to drain away the excess condensation.
10. Turn on the combination boiler, and it should immediately start making hot water.
11. Remove and discard the old boiler and water heater.
Expert assistance with this project was provided by Barry Cullen of Comfort Technology [www.comfort-tec...].
Richard and Barry installed a condensing wall-mounted boiler, model number E75C, manufactured by Rinnai [www.rinnai.us/]
About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers-and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.
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How to Install a Combination Boiler/Water Heater | Ask This Old House
/ thisoldhouse

[@marcosmota1094]

I know it's an old video, but it's nice to see Roger!

[@jnictv1075]

Where in this video is Roger????

[@jakegardiner6304]

@@jnictv1075 the end of the video... did you even watch it?

[@Lionscall111]

I loved how they picked up the unit by its internal and valuable sensitive parts to hang on the wall.

[@TheOneWaja]

Im from the UK. i have a Vailant turbomax 242, over 10 years old in my home. im a gas engineer and have barely had to touch my boiler other then to service it. Get your boiler serviced yearly, properly and it should last many years like mine. many new combis are made to break. however there are a few good new boiler makes out there which will last years. for example, the new Baxi range. Make sure your boiler has rigid materials such as copper and brass and my word, what a range of boilers they have. very innovative. i recommend all to have a look. easy to maintain and repair, what can go wrong!

[@tommytmt]

How do you feel about Rinnai and/or Naven? I’m in the US and I’m not aware of whether or not we can get Baxi here. I don’t know of any contractors who install them in my area. I’ve heard of them and from what I’ve heard they’re fantastic units, I’m subscribed to a HVAC contractor from the UK.

[@juanfernandez1180]

@@tommytmt stay away from navien very fragile units I've installed many the stainless steel heat exchanger is horrible gets clogged very quickly and the acidic byproduct of the unit will eat through the heat exchanger quicker than other units I've installed. Being a plumber myself I just installed a cast iron unit and it's amazing never gives me problems like the wall hung units do and run it at 83 percent efficiency... wall hung units are great on efficiency but what's the point of you'll end up having to change it in 5 -7 years which I've done many so... and that's with maintenance can't imagine how long it'll last without...

[@1chish]

I first fitted a German made Vaillant combi boiler over 35 years ago here in the UK. It lasted longer than my marriage at 20+ years! I have fitted a few other makes for friends. Ideal, Baxi, Worcester (Bosch). All have lasted with annual servicing to keep them 100%. Last one I fitted was an Ideal Logic 30, cost me about £750 ($1060) and I fitted it in 2 days replacing a 30 year old floor mounted Mexico. Have to say the UK flue and intake systems seem to be far better than that US version. You hardly notice them as they combine the two into one pipe. Different Regs I suppose.

[@H4zuZazu]

And the combined flue pipe is more efficient, couse of Heat recover to preheat the combustion Air.

[@RossKempOnYourMum01]

What's your gas safe number?

[@AMD1]

Grumpy Electrician They're called Concentric vents in North America, and they're commonly used.

[@gfriedman99]

AMD1 nobody has them

[@grizzlybear2702]

1chish its very sad that in today’s modern world a boiler can be more loving and caring than a wife

[@PatrickvanderStoop]

this one i love, because this heater is made in the Netherlands... so two things i love the most... America and the dutch heaters..... great show guys..

[@larrycurrier290]

I'd like to see a video of years later and see just how happy this lady is with this thing. Don't ask somebody that's just put one of these in how they like it asked somebody that's had one for a while. This thing is very low water capacity I can imagine this thing having some amount of thermal shock when it sucks that nice cold water back from the system.

[@OMGWTFLOLSMH]

They've been using these units all over Europe for decades. Americans are so set in their ways and resistant to change. They sized the unit for her hot water requirements and the size of her house. Not sure what you mean by "very low water capacity". I bet you're a climate change denier and anti-EV too.

[@larrycurrier290]

@@OMGWTFLOLSMH as a 40-year plumbing and heating guy I probably know a little bit more about this than you do pal. As far as climate change goes, there was an ice age before there was an automobile And you're into electric vehicles I guess you don't realize where electricity comes from number one and number two the kids that died in mines mining lithium and cobalt for your Tesla. If you don't know anything about the life expectancy of certain heating equipment then you probably shouldn't say anything at all.

[@joecliffordson]

@@OMGWTFLOLSMHwtf. You could not have just quit at Europeans have enjoyed these for years? Who hurt you so bad you have to jump to conclusions about a little question. Then you go on to use the most divisive terms possible that have no meaning. Tell you what. That attitude does not sell conservation. Good ideas that deliver what the consumer wants sell conservation . What is a climate denier anyway? You mean like those residing at the space station? Get with the program and sell the idea of responsible care for our planet if you want to be conservation minded. It takes a lot more than pointing and saying climate denier. EV denier. Maybe you need a psychiatrist.

[@etem.a.4974]

That basement is so neat ... Organized .... Wow...

[@jacob60617]

I had one install on my home. It’s really good. But can be expensive to maintenance if it breaks down

[@paulg444]

I like the old cast iron system.

[@Shao-wen_Wu]

"Can it heat the house and produce domestic hot water at the same time?" thank you for including that question, I have that one too.

[@caru3257]

It has priority for hot water.

[@autonomy5649]

The internal diverter valve reroutes the water either to space heating or water heating. The space heating water basically starts to cool off during a call for hot water. In the worst case, if someone takes a long shower, you'll have barely any heat for that time. Maybe some day someone will put in a valve that can be partially open and the boiler just modulates up to handle the load.

[@M13x13M]

No, you need a combo core with a water tank to do that.

[@reubenyoder6990]

Use a Navien combi boiler and you can vent it with 2 inch pipe.

[@CastleBomb44]

Ok I am convinced. I really want my first house to have a Gas Combination Boiler/Water Heater

[@Maxid1]

4:43 "Ok Ma'am, let me explain the hydra you have sticking out of the side of your house."

[@thatoneukrainian649]

And it was on market, this is rinnai q series, and they have good termination kits.

[@guzman9011]

Yeah they could of just installed two down facing pipes about 15 inches apart

[@harrisonherring9194]

we have Coaxial flues in the UK for all boilers. does the job of exhaust and intake, whilst looking so much cleaner on the wall.... those two pipes are so ugly... or why not just move them apart, with a flat vent???

[@squidproquo2241]

OK Idiot let's hear what your problem is.

[@squidproquo2241]

@@harrisonherring9194 _ Or, why focus on the looks of the pipes instead of their efficiency? This mentality that focuses on how pipes looks like instead of their function is uglier than the pipes ... Even when it comes from a social class focused Britishit

[@Ringele5574]

Thanks TOH for posting some of your programming. I really enjoy them. Please don't listen to all of these 15 y/o experts in the comments.

[@mnf65]

15+ years of experience not age. I would never vent that close to a window. Code is bare minimum, always try to exceed code.

[@GalaXy808]

wow? I got it,sounds like better than the regular water heater

[@proverbs2life]

Combi units can definitely appease almost any home. They are able to be installed in a cascade to add more than one unit for higher demand. Plus you can always do domestic and hydronic heat from separate tankless units

[@fgcbrooklyn]

Do you have a suggestion about the BRAND? I am looking into this but as usual the web is full of junk information and recommendations (secretly sponsored)

[@Cody-ye3ye]

@@fgcbrooklynnavien is garbage

[@omaxman1]

can't stop watching these videos..

[@onyxe.s.4349]

we have had them in the uk for over 20 years

[@onyxe.s.4349]

i don`t like the venting it`s bad

[@briancnc]

+ONYX E.S. There has to be a more aesthetic way to vent that, I agree the PVC elbows like that are by no means attractive.

[@acardboredbox]

+briancnc being white they look bad, but paint them black or the house color and they'd look fine.

[@Sawashi32]

Congrats to you and the UK but these things are junk anyway.

[@MKRM27]

+Sawashi32 They aren't junk in the UK; perhaps they're just better quality engineering. As for the venting, I've never seen one like that.

[@jeffwright5794]

Seems like a great idea..until it breaks down. Parts take days to weeks. Which is fine if you have backup heat for the house. Inevitably the thing will fail when it’s the middle of the winter. When that happens it’s quicker to replace the whole unit than waiting for parts. Supply houses usually have entire boilers in stock. Not so much for parts. Also when using radiators or base board heat you still need to run the boiler temperature at 180deg. Which reduces the efficiency substantially. These work best for radiant in the floor heat where the water temperature is usually at 130 deg. There are multiple plastic parts, sensors and control boards Also yearly maintenance must be done to keep the heat exchanger from becoming plugged with minerals. I’ve worked on these for decades, you won’t find one in my house.

[@Keegeth]

Rinnai and Naviens are very easy to get parts for in RI. Lochinvar and nti are a different story.

[@jeffwright5794]

@@KeegethIt recently took a week to get a three way valve for a Navien up state NY in a unit that was less than a year old . Other similar type units I've worked on I've always needed to wait for parts. My comments stand.

[@Keegeth]

@@jeffwright5794 that sux. For a 3 way valve for an ncb unit that had a bad 3 way valve I called plumbers supply and they had one on hand. An ncb heat exchanger was leaking combustion gases in the cabinet causing cabinet temp to rise, causing oil to be extracted out if the plastic parts and the pcb board to go bad took 2 days.

[@adriansmith7104]

What about the Polaris isn't that brand supposed to outlive you and your next generation. Is not tankless but it works for both.

[@jeffwright5794]

@@adriansmith7104 never heard of one up here and don’t have a local supplier for parts either

[@verbotn]

When I install condensing gas appliances, I will put the air intake and exhaust as far apart as possible. It made me cringe to see them putting the two side by side as that increases the chance of the air intake being subject to frost closure during extremely cold weather, when some of the moist exhaust is re-ingested and creates a hoar frost accumulation in the air intake. When the air intake is partly or entirely blocked by frost or any foreign material, a sensitive air-pressure safety switch will prevent the appliance from firing. The region they're installing in might make this less likely, but I'm in Calgary, Alberta so we do get some very cold spells during winter where this is a factor. If I am installing multiple condensing gas-fired appliances, I will bank all of the intakes together and all of the exhausts together with as much space between them as site conditions allow, though generally 6' is plenty. There is usually a prevailing wind direction, so I'll install the intakes upwind of the exhausts for the same reason. This past winter I had an interesting service call at a clients where his condensing gas furnace was not firing, upon arrival it had a fault code indicating a combustion air problem and I could hear whistling around some of the burner enclosure, so I suspected something blocking the intake. I went outside and found a plastic packaging 'pillow' from an Amazon package that had become lodged in the air intake, that was a new one, random garbage blowing in the wind that plugged the combustion air pipe.

[@charlesstevensEnki]

Once the scale is built up in the heat exchanger efficiency will drop. I like the separate heat exchangers just in case they have to replaced.

[@morbo3000]

Descaling by periodically pumping an acid (usually vinegar) through the heat exchangers is recommended if you live in an area with hard water. At 5:25, you can see that there are fittings installed for just that purpose.

[@Anakwad]

Thanks for the information ! I love This old house.

[@mr.dahliaking.202]

I hate my combi boiler because of the annoying cold water intervals whenever I turn off the hot tap and turn it on again. I changed my setup. I still keep my combi boiler for heating the house and basement, but the how water part for the taps I converted into closed zone, and by saying that I mean that I bought tesy bilight combinated 150 liters electric water heater with a copper spiral inside, and I am using termosthat to call the pump into action and water is circulating and the boiler thinks it's heating hot water for the taps when infact it is heating the tank water heater via spiral inside. It's like heat exchanger and it works great, no more cold water intervals and plenty of hot water pressure. I suggest this convert to everyone who hate the hot water fluctuation when the tap is turned on/off rapidly.

[@jeanpierre-louis3986]

Hi , I am very interested by your experience could send me some pics or a video. I wanna modify mine too. Thanks! My email: [e-mail]

[@jonminnella4157]

Great technology however when it brakes its expensive old boiler uses lots of gas but hardly ever brakes

[@captaingreenhat]

Exactly. With a little extra effort she could have kept her old equipment and still had a hybrid and efficient modern system.

[@chooch5728]

Everything is expensive to fix. old or new

[@jochimbenschneider1915]

Electric boiler is better

[@martinheatingcoolingmartin4693]

Yeah, I got a know that boiler over and over again because they are not reliable but that’s with any combination wall boiler, very touchy and expensive to repair. One major repair out of warranty you might’ve just spent up all your savings towards that one repair. But overall, they do save space they are efficient. They are reliable and they’re the way of the future versus big cast-iron boilers. They do make better sense as they’re more on demand. Just expect to replace them a lot sooner than the large cast-iron Boilers.

[@46fd04]

I just had a similar unit installed at a family member's home. The company did not install the outdoor temp. sensor. They said it causes too many problems.

[@bmkolb]

I love cast iron boilers the Combi is very very expensive to repair and service. Blowers cost from 300 to 600 plus labor. Controls cost from 350 to 1,000 Anyone one of those two parts go bad your savings is gone on efficiency. The boilers might last 15 to 20 years vs cast iron 30 to 50 years

[@gfriedman99]

B K like everything else nowadays it’s disposable. If it breaks you throw away and buy new

[@DW-bo3qw]

You would be lucky to get 15

[@hughjazzole2037]

what blower?? its baseboard

[@Mihogan]

This new tech is really cool but I prefer my old school cast-iron boiler. So much more complication, maintenance, and room for things to inevitably go wrong, all for maybe 15% more efficiency. For my home that would only equate to maybe $200/year saved - I'm sure the maintenance costs are around that for this unit.

[@hughjazzole2037]

Youre a plumber that makes $$$ pushing those outdated pieces of crap??

[@joshuacassino7297]

What’s a great combo brand?

[@Jason-wc3fh]

Hack job venting install. Should use the deb4 deburring tool on the pipe before fitting them together and gluing them. Without deburring the end of the pipe, the bevelled end from the cut will push the glue out of the fitting and make for a weak joint.

[@frmerrin2]

Yeah right.

[@stevepailet8258]

as small a combi as this is. There are times when the heat call is still smaller than the combi will produce. So this is a great reason to keep the old tank water heater as a ballast tank with enough warmed water to supply the radiant without short cycling the combi. This seems to happen most often with using radiant heating as opposed to the convectors which usually have a much larger btu heat call. Radiant floor (could be in the wall or ceiling) spread the heat load and will have cooler water flowing than the convectors

[@spencerwilton5831]

Steve Pailet a decent combi will modulate down to 2-3kw, sometimes lower. Short cycling shouldn't be too much of an issue on a well planned system.

[@garethw001]

By the same principal could you use a traditional, inexpensive electric water tank to 'pre-heat' the water supply for the combi boiler to reduce the amount of gas used? (and fossil fuel burned)

[@johnburns4017]

ATAG, Dutch, re-badged by Rinnai. Quality. But the control system is complex. A pity Intergas, Dutch again, do not sell in the USA.

[@mysticpizza02]

Would have liked to have installed an ATAG but it was very expensive settled for an Alpha combi hope it lasts my previous standard boiler hot/cold water tanks lasted 34 years was very inefficient towards the end it was an Ideal mexico.

[@michaelsmith9034]

Homeowner will probably regret removing that old boiler. Far more dependable.

[@jamesvelvet3612]

Original 1962 American Standard boiler and Westinghouse burner. Boiler has a coil, no external tank. 60 years old and works fine. So simple a cave man can fix it ;-)

[@simpleagain1]

Throughout history cavemen have always received an unfair knock

[@edyflorida6344]

i m so happy follow ask this old house on youtube

[@victorguery1492]

Do I need an external pump for the heat loop? Of is the internal pump strong enough for 3 zones?

[@matthewkromer9256]

I love my new heating system.... don't mind my pos rusty air conditioner...

[@heslind]

Can’t wait to have one of these installed in my house

[@heslind]

@Kevin Edwards sorry to hear this. How often does yours have issues(

[@wileecoyote5749]

DO NOT DO IT

[@heslind]

@@wileecoyote5749 haven’t yet but will need to replace current boiler soonish. What do recommend

[@simpleagain1]

@@wileecoyote5749 W H Y ?

[@wardope]

Just installed a 30Kw air-to-water heat pump that runs off my Solar panels and wind turbine. free heat and free electricity. all the electricity I produce that I can NOT use or Store on the battery pack is being sold with. it's perfect for a 523901 Square inch house! alto this is a fare more expensive purchase up front but the entire system will pay it self off in about 10 years.

[@SalimKhan-gk1fh]

Combi boilers are not junk, and are fitted in 90% of British homes, yes, the cheap ones are junk, but fit a good quality German boiler and all will be good, in us , Canada I think viessmann are the most popular and efficient choice

[@gfriedman99]

Salim Khan what, no chinese models? I dont want to spend a fortune on this.

[@greentea7539]

We just had one installed and i been so worried that it is close to a window. I see though 12" is enough. Things have changed!!

[@dorianlord6576]

I would definitely want the outdoor venting pipes on the side of the house--they are a bit unsightly.

[@beoutside]

There are much better low profile venting options.

[@OMGWTFLOLSMH]

Yeah, that was a cheapy install. There are much better solutions.

[@tre2472]

would you recommend the water in this system be treated? like a water softener? cast aluminum?

[@captaingreenhat]

Kills me how quick this old house is to punch holes in exterior walls. 😱

[@chipdayton1625]

So you want them to vent the boiler into the basement?

[@jaredsmith1871]

@@chipdayton1625 Why couldn't they run an intake and exhaust vent up the existing chimney? They make concentric pipe for this purpose. Then you don't penetrate the wall with unsightly and possibly obtrusive venting. The woman moved the units to the wall but now has an unused chimney.

[@chipdayton1625]

@@jaredsmith1871 That can be an option sometimes.

[@ozm8642]

USE A PANCAKE TERMINATION! Looks so much better than seperate or concentric IMO

[@brendanbussell5707]

Hope they explained that as Long as you are using hot water you are not heating your house have five people take a shower for over an hour on a 20 degree day in a old house and watch the temperature drop in a heartbeat great idea for energy saving but not practical for extreme cold should heat both at the same time to prevent the house from getting below the desired temperature

[@edvinasmi2174]

Brendan Bussell

[@KaFei82]

For more than 2 people in one house I would prefer a sideby water boiler (DMHW) (heated from the gas heater) for more comfort and instant hot water.

[@lucasvargas4580]

hello i´m from south of brasil, and we used this wather heater a lot of time, we never used a boiler, we used a gás passager. He just work wen you open the shower, when you closed he stop whith a gás.... This way we can saver money!

[@bwckplumbingfixtures1864]

I wouldn’t be effective

[@marshall5132]

all these how to videos are in homes that are freakin ridiculous. So much space to work... where is this paradise?

[@Danny-fs1hk]

Love this show!

[@johncoen869]

You can get combi`s with hot water storage.

[@jeffreyjohn2037]

You can get a condensing boiler with a indirect water heater.

[@BetoTheButcher]

5:51: Nice to see Kurt Angle staying busy.

[@heroknaderi]

Incredible

[@MrFy2013]

I love how many commenters here know better than Trethewy. Or think they do. #Dunning-Kruger

[@kyleholland527]

Dunning Kruger IS the internet. And the White House.

[@SureShotImages]

Clean install boys! #Nice.

[@DuncanCunningham]

New? In the US maybe. Standard boiler setup in the UK since the early 80's though I'm not sure we had instant on demand in a combi until the 90's. Every home should have one if they use gas heating with radiant panels, baseboards or flooring. I'm sure they could connect up to a heat exchange air handler too but that could get expensive to install and we all know that up front costs, in the US, is always considered over running costs.

[@knighthvac4876]

+Gravel Trap King Yes new in US less the 10 years , Most are installed wrong here in the U.S. , Customer have the Out door reset removed do to poor heat output. Most homes are under radiated with baseboard, Original boiler were pushing out 180 to 200 degree water. How often are boiler replaced in the UK? Here in U.S. most customers are expecting 20-30 Years. TY

[@DuncanCunningham]

Boilers replaced in the UK?, I'm not sure. In the house I grew up in, they replaced them due to technology and efficiency improvements not mechanical failures. My parents replaced the coal boiler in 1982 with a gas version and they replaced it again in 1998 to get a better one that used less gas, nothing wrong with the older one, it just was too inefficient to run compared to the newer models. I'm installing a boiler to heat radiator panels in our home in Utah (to match our UK home setup) they are great at keeping the rooms warmer, I hate the too hot, too cold air handler feeling. I want gentle heat that is cheaper to run. costs a little more to install but better in the long run, and it can easily be attached to solar collectors to heat the water anytime of the year so the boiler has less work to do. As long as its not snowing the typically clear skies in Utah allow solar collectors to pull in lots of free sun heat.

[@gfriedman99]

Knight Hvac 20-30 years??? My cast iron American Standard gas boiler is 60 years and still runs great with very little maintenance.

[@hansi6606]

Regarding SPIROTRAP and SPIROVENT - wrong installation: At 7:17 we have a close look on how they were installed. Doesn't make much sense. The Spirotrap is mounted correct, collecting all the debris from the hydraulics BEFORE entering the water heater and pumps. The Spirovent however will work best, when mounted right behind the water heater at the hottest spot in the system and in front of the pump. It collects all the air bubbles from the water, just as you can see them when boiling water on your stove. The process continues over and over and makes the water adsorptive. It means, that the water will now collect any left air from the system by dissolving it. The water passes the heater again, solved gasses become bubbles, which are again seperated at the Spirovent. If mounted correctly, you will less likely face any issues with air in the system.

[@josht8288]

Oh goody' so if one small thing in the combi failed you lose both hot water and your heating. I would have left the old setup in place but isolated from the sistem as an emergency backup.

[@iandouglas4992]

That would be extremely combersum on the heating side, those systems have to be bled.

[@picklerix6162]

These combi boilers are expensive and so are the parts (if you can find them). For example, that Rinnai condensate neutralizer kit costs $122 but you could make your own out of PVC and limestone for less than 20 bucks.

[@MrPoofydrop]

i know i made one from twizzlers and chopsticks and an old condom inside of a musturd jar

[@indioflechudo6221]

look at this guys, installing exhaust pipes next to a window..wooow what a death trap.

[@frmerrin2]

50,000 BTU and up can be within a foot of a window when it's a direct vent appliance.

[@roberthudanish7405]

@@frmerrin2 it is 12 inches with a concentric kit or terminal vent kit. it is 4 feet the way they did it.

[@frmerrin2]

@@roberthudanish7405 Wrong,it's 12 inches for direct vent which is exactly what they did, if they were merely exhausting flue gas and drawing combustion air from the basement than it would have to be 4 feet.

[@Mike-uf7oc]

I have Navien ncb 190/080h goes off on thermostat but it keeps running no/off every few minutes

[@jaymorin4466]

Don’t get to comfortable holding that expansion tank as you install that boiler. Most vulnerable connection on that boiler!

[@macpatel7810]

Lol. I was thinking the same...

[@DavidWilliams-wj4sc]

Limitation 3. It can't cool your house like a forced air furnace/AC combo. Time to add some mini splits. Should have touched on that I think.

[@Jallelab99141]

How come you did not use a low profile termination kit on the side of the house for the vents? Something like Rheem Horizontal Vent Termination Kit, or the IPEX Plastic Side Wall Vent Kit, or Trane BayVent?

[@MrPromerican]

I see hydraulic, air and dirt seprator, but where is the expansion tank? I guess rennai doesn't require it? But hydronic principle does...

[@jamesfisher5391]

it's the red thing inside the boiler. You could add another depending on the water content of the heating system. 3:36 you can see him trying to break it off while hanging the boiler. lol

[@Spiek-ICT]

Funny, the heater is from dutch manufacturer Atag. We use this type of combi heater for year's.

[@elliottdiedrich3068]

In the third year when the computer motherboard craters, how much will it cost to repair the machine to running condition?

[@peterryan7827]

We are at prsent deciding on a combi type boiler ,and enjoyed this very helpful video,i wonder could you explain to us what those other pipe connections units you have had to fit underneath the boiler ,one i assume is a pressure vessel and may be a non return valve,but you have a massive cast iron unit on the gas,hope you did not mind my asking,

[@Slowhand871]

There is no cast iron on that unit.

[@goudsekaas5673]

From left 2right: - outgoing hot water for heating - outgoing hot water for shower and sinks - incoming gas - incoming cold water - return of the hot water from heating

[@billcooper6674]

Ya I would of tried to fix it. To toss out a 4-5 k+ unit after 4 years is a waste of machinery and money even if you have lots of it. I do agree with most of the comments here about Tankless, it is a hard sell and the savings are not that great yet what 20 to 30% of your gas bill wow maybe. You need a few things working for you if you are even thinking Tankless. 1. A (good knowledgeable Di Yer) because it is way to expensive to have a authorized installer- plumber do the work $900 to $2000 + Payback is way down the road if ever. A lot of Plumbers run from this type of installation, way to many headaches and repeat calls but they are getting better and so is the technology. 2. Find a (manufacture that will allow a Di Yer to install the Tankless and give you a warranty of parts) on it like Rheem and Nortiz. Please Read the fine print in the warranty section before you spend your hard earned money, many companies will cancel the warranty unless someone with a licence is installing the Tankless. 3. Don't even think of owning a Tankless without a recirculation pump/system. The wait for hot water and the waste of water down the drain is way to much. 4. Federal Tax Credit may still be around in 2018 up to $300 need .82 EF + rating. I am about ready in 2018 to jump into a Tankless probably Rheem or not still desiding. I will spend 1 to 1.5k on it knowing I could replace my current 18 year old TANK model TWICE for that $amount$. If I have no breakdowns in 10 years I will be lucky, if I do its back to the reliable tank model. I'm all for you Di Yer's Good Luck.

[@TRaySteeves]

Bill Cooper and all a person needs to do is turn down the internal thermostat! Does anyone really need 120°F water coming out of the tap?

[@silk33105]

@thisoldhouse this looks like a wonderful system but you didn't talk about price. how does it cost??

[@malachy1847]

Greetimgs from Ireland....They are mainstream over here in Europe so in that regard once sales in North America ramp up, the price will tumble..[.have a unit running off bulk kerosene unit installed in a rental property for the last 10 years ours is a 'Boiler house ' model ..... and apart from annual service zero issues] grantengineering.ie/high-efficiency-heating_products/best-oil-boiler-brand/

[@andreyyaromich8277]

10g+ installed

[@autonomy5649]

The units aren't very expensive, relatively speaking, but for some reason installing them the labor jumps 3x despite all the propress, premade manifolds, and combi valves that are out there these days. $10K is about what I've heard, for labor only.

[@MrPoofydrop]

Ive never seen flue pipes placed in such close proximity to a window. The flue pipe exhaust fumes will go right back into the house. Especially that house since they have an air conditioner in the window. The air conditioner will pull the exhaust fumes into the house when its running. im shocked that was allowed. No primer on pvc either? what state are they in and do they have inspectors?

[@rainmaker3700]

@@brennatrix I believe code is 36" from any opening.

[@rainmaker3700]

@@brennatrix Navien and Rinnai require 12" between the flue and the intake. But UBC requires 36" betweeen any opening and the flue pipe. Atleast that is what is enforced in my area of Northern Cali. I install 10-15 Navien boilers/water heaters a year.

[@danpham3804]

Do we have electric unit? thanks

[@billdohinuk2679]

What about having one of these in my diy RV? Have heated floors and hot water, all-in-one?

[@joeellestad8912]

Looking to heat a 2000sq radiant house along with hot water for 2 bathrooms and 1 kitchen. What is a good combination unit? Live in northern MN and will also have a outside wood boiler for the winter. Is it a good idea to have the propane as a backup unit when the owb is in use?

[@spencerwilton5831]

Joe Ellestad In the U.K. 2000 sq foot would be considered a generously proportioned family home. Two bathrooms is a stretch for most combis if they are used at the same time- it's possible, but showering performance might be disappointing when the incoming water temperature is low. Although combi boilers have been widely used here for decades, for larger family homes with higher hot water demand a mains pressure hot water cylinder is still preferred. We use one boiler and a three port valve to serve both the cylinder and central heating. It eliminates the need for a separate water heater, allows for a backup (electric element in the cylinder) and means your boiler is in use daily rather than sitting idle for months at a time during summer which helps prevent parts seizing etc. It's also possible to integrate a wood boiler into the system by clever plumbing so you can run on either system or even both at the same time. There are various methods of doing so including the use of buffer tanks or simple manifolds that serve as a central point for both boilers, the heating and hot water circuits and allow for any combination of heat production and consumption.

[@joaquimlloren6769]

Of course in winter you will certainly notice that youre getting enough heat in the house if its 10 -15 minutes thats long enough

[@CRgamingMSFS]

I bought a lochinvar noc199n. Mine did not come with the black peice yours has underneath. Do I still use the old circulator pump? Also, on the old boiler the out and return pipes were kept separate. The diagram shows a bypass pipe. With the bypass pipe how does the water get forced into boiler and not just circulate cold water?

[@ralanham76]

I don't have gas and live in FL why do I watch these?

[@thatguy4234]

Lawd I’d hate to troubleshoot that thing

[@xiaojie895]

why some contractors put a storage tank beside the wall mount boiler but the demo installation on this video did not do it?

[@dfiore916]

Is that thermal backing necessary? I wasn't sure if that was for code, aesthetics, or practicality.

[@dantebbe]

How much does something like this cost? Efficiency is great, but it it's not going to pay itself off for 15 years, most of us can't take the plunge.

[@Carmeri1928]

How much is the price

[@SunSandAndSea]

Would be great if you showed an installation with a combi unit and a new Style forced air handler using a coil. Seems to be the future. Combi Runs the whole house.

[@spencerwilton5831]

Living the Spu Life Forced air is not the future. We ditched it in europe forty years ago! Who wants all that noise, drafts, dust blowing around? Underfloor heating is the best option, otherwise ordinary radiators.

[@SunSandAndSea]

@@spencerwilton5831 maybe so. But i havent seen one home running that setup in my area. Toronto canada. 99% run gas forced air furnace

[@autonomy5649]

@@spencerwilton5831 Seems like these combi units have been getting popular in the US only in the past 10 years or so. We're very much behind, and there's a lot of slap-dash construction over here. Underfloor heating is nice but not if you have to rip up floors and not sure it'd work all that well in a drafty Minnesotan house when it's -30 deg outside.

[@fortmcmurtry]

@@spencerwilton5831 Only high end homes in north america are designed with infloor heating. 99% use forced air and yes a hydronic air handler is the way to go if you are coming from a traditional furnace

[@mackenzierinier4956]

1. No primer on the vent. Asking for a leak. 2. Vent to close to a window. Sure it tells you 1 foot in the book. Every code guy around requires 3 feet 3. With a two story home and those convectors. The built in expansion tank is not going to be large enough. the relief valve is going to be popping. 4. Not a fan of the Grunfoss 3 speed pumps for that system. The Taco 3 speed will do the same job. But if the pump goes out at night or over the weekend. The customer can swap to a different speed to get them through till you can get a replacement. 5. When installed right. Those are good systems. If the customer has any kind of demand for hot water. Always better to install an indirect.

[@mudbutt7224]

Common sense let's me know ike has no idea what he's talking about

[@san379]

better than a house fullllllll of ductwork but no A/C

[@ukar69]

I’ve got a combi boiler that sits outside. Trouble is mice decided to use it to nest in. There’s no visible gaps but they still got in. It stinks when you open it.

[@negritorican]

Lose power because of a storm, enjoying taking cold showers until the power comes back on.

[@MMKLYH]

eNaRDe and how would you not have a cold shower if your power was not on if you had a cylinder, I mean unless you’ve got a gas fired cylinder that has a thermocouple your gawny get no hot water regardless

[@knighthvac4876]

High up front cost no pay back! Lucky to last 10 years! probably leaking/ rotted out today. Good luck finding someone to work on it!

[@briancnc]

+Paul Ricardo All of the companies out here service these, and I seriously doubt it's 'leaking/rotted out'. Heating water 24 hours a day regardless of the demand is so inefficient it makes you wonder why this isn't the standard for single family homes here in the US. And with respect to 10 years, how long before a HWH busts all over your basement these days?

[@acardboredbox]

+Paul Ricardo It uses all the same materials as a standard system with less overall energy input. Why would it degrade faster?

[@jason-ge5nr]

+Paul Ricardo sorry ma'am ill have to order your 500 dollar heat exchanger... should be here in 2 weeks... or 800 dollar 3 stage gas valve...

[@acardboredbox]

+Albion Laster that's cost not longevity

[@knighthvac4876]

Not All service/plumbers work on them!! Gas suppliers will not cover them in service contracts! Most leak at Dielectric unions and low loss headers,Not covered under warranties. My guess is too many dissimilar metal , cast iron ,steel, aluminum, brass,copper and ph levels. BTW this install is awful , No way of isolating and descaling plate exchanger also no sediment trap to catch all the 50+ yrs old rust from convecters radiators . I service these all the time, When something Fails it costs Big Money and long down time waiting for parts.. Yes a 40 gallon waterheater will only last 8-12 yrs. But replacing it is cheap and any plumber can do it in less then 3 hours. These Mod/Combies retail for what $4k..Cast iron Boiler are half that and last twice as long..

[@MassEffectFVR]

"modulating gas valve" looks like we will be replacing it next year

[@thomaspease208]

could you use this in a commercial restaurant

[@MemoGrafix]

I can't do both heat and hot water at the same time, not good for Me.

[@demil3618]

Amazed they still don’t work in metric... But why not install a condenser builder that recycles more of the exhaust heat with a pipe-in-pipe flue?

[@matt21_22]

The additional cost in maintenance thats Recommended plus yearly safety check on the wall hung makes it unattractive. As well as part availability. if the space is limited you may have no choice . Tank water heater is very simple and less things that can go bad. I had mine for over 13 years with limited maintenance. I work on heating and cooling systems everyday the last thing I want at my home is a unit that needs alot of maintenance. I would sacrifice some efficiency for a unit that will last for many years and less break downs.

[@spencerwilton5831]

Ken Ortiz all gas appliances should be serviced annually though... doesn't matter if it's a modern combi or a floor standing cast iron installed by your grandparents in 1950. Costs are the same- there is nothing more to servicing a combi, it's just case removal, clean and check, possibly replace a $5 thermocouple and burner seal. Close up again, check gas pressure and combustion gasses- exactly the same as any other boiler / furnace.

[@fadetounforgiven]

What I don't get is if the boiler already has a circulation pump inside, why would it need another outside?

[@mackenzierinier4956]

fadetounforgiven primary and secondary pipping.

[@BaconJD420]

What is the brand Combi was that?

[@M13x13M]

The required maintenance of the new unit will more than off set any energy savings and the electronics will fail and be unrepairable and overall will have 1/3 the life of the old unit.

[@smartchip]

In which areas or states do heated hot water systems? Intergas are the best combiboilers,

[@leoionita8083]

Unless you have more than one heating zone set up, you don't need the other pump. The boiler already has one.

[@evanrysdyk6651]

Wrong, pump will not overcome house head pressure. Pump is only for boiler and low loss header flow.

[@spencerwilton5831]

Evan Rysdyk Please explain how we manage to make these work in Europe for houses with twenty plus radiators yet no low loss header or second pump?

[@daversj]

Disappointed to see iron pipe used instead of copper or brass on a new install. Saved maybe $100 in materials but will have more rust in the system, especially with a plate heat exchanger on the DHW side.

[@autonomy5649]

Agree. Although it does look like they installed a Spirovent dirt separator although not on the return side as recommended (next to the Spirovent Jr. air separator?).

[@hideouspenguinboy]

Why do you use copper piping close to the heater and then pex later on?

[@Bremend]

Copper is harder to route and expensive so it doesn't make sense running across the entire house if they don't need to. On the wall, they can either do copper or pex, but the manifold would always have to be metal for rigidity and holding back the effects of water hammer

[@allentoyokawa9068]

Made in Japan!