How to Install a Reserve Tank | Ask This Old House

In this video, This Old House plumbing and heating expert Richard Trethewey installs a reserve tank so a homeowner can finally fill their tub with hot water for a relaxing bath.
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Plumbing and heating expert Richard Trethewey helps a homeowner solve a hot water shortage problem. Thinking that they had an on-demand water heater, the homeowner couldn't understand why the water from the tub spout would cool before the tub would fill. Richard discovers it's a combi unit with a water tank and helps the homeowner solve the problem by installing a reserve tank.
Difficulty: ⅖
Time: One day
Cost: Around $2,000 including the tank
Where to find it?
Richard Trethewey helps a homeowner understand how different flow rates in water fixtures could be the culprit behind a bathtub that turns cold after only being halfway filled.
Richard discovers the tankless water heater [www.thisoldhouse.com/plumbing...] can’t keep up with the tub spout’s flow rate. He suggests installing a separate 80-gallon reserve tank [homedepot.sjv.io/6ekgLK] that can easily handle the 60-gallon soaker tub. With the assistance of a plumbing specialist, an ideal location for the new unit is identified. Richard suggests an area near the existing tank that isn’t prone to freezing.
After disconnecting the electrical supply, connect the tankless inlet to a bronze or stainless-steel
circulator. On the tank, tankless outlet, use both thread tape [homedepot.sjv.io/m542qe] and pipe dope [homedepot.sjv.io/daK9DM] and connect a 3/4 inch tube adapter [homedepot.sjv.io/75XJ6A] and connect this to the hot tankless coil outlet on the boiler. Use both thread tape and pipe dope to connect a 3/4 inch NPT brass tee [homedepot.sjv.io/eKnAWr]. In the run of the brass tee, install a 3/4 inch NPT brass Ts [homedepot.sjv.io/AWgEN1] long element for hot water heaters, as required by local codes. In the bottom of the tee vertically down, install a 3/4 inch NPT x 3/4 inch tube adapter. Then install two 3/4 inch sweat street 90-degree elbows [homedepot.sjv.io/3ekdNB]. Fill the storage tank by opening the cold water shut-off valve. Make certain any drain valves are completely closed. Purge air from the system by opening a hot water outlet at a fixture in a kitchen or bathroom.
When water flows freely from the outlet, the system is purged. Set the storage tank to the desired
temperature. Boiler high limit should be set at least 20 degrees F higher than the storage tank temperature setting.
Water heater products were manufactured by Heat Transfer Products (HTP) [htproducts.com/] and Jomar Distributors [www.jomardist.com/].
Expert assistance provided by Papalia Home Services [papaliaplumbing.com/].
Looking for more step by step guidance on how to complete projects around the house? Join This Old House Insider to stream over 1,000 episodes commercial-free: bit.ly/2GPiYbH
Materials:
Reserve tank [homedepot.sjv.io/6ekgLK]
Expansion tank [homedepot.sjv.io/6ekgLK]
Thread tape [homedepot.sjv.io/m542qe]
Pipe dope [homedepot.sjv.io/daK9DM]
Bronze pump [homedepot.sjv.io/ZQVyGq]
Copper piping and fittings [homedepot.sjv.io/WqOGkM] (press or push to connect)
Tools:
Wrenches [amzn.to/3nSEoL1]
Pliers [amzn.to/3VVe53y]
Hose [amzn.to/3LNzeYC]
Bucket [amzn.to/3I0oxAL]
Tubing cutter [homedepot.sjv.io/9gLXyQ]
A Pro Press [homedepot.sjv.io/DKWqxq] is optional if you plan to do this job more than once or twice a year.
Plus, download our FREE app for full-episode streaming to your connected TV, phone or tablet: www.thisoldhouse.com/pages/st...
About Ask This Old House TV:
From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. ASK This Old House helps you protect and preserve your greatest investment-your home.
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How to Install a Reserve Tank | Ask This Old House
/ thisoldhouse

[@janedav7310]

This was an exact replacement for the old one that lasted about 10 years. kzbin.infoUgkx7yWIKcrbA9KMHkGSfcgxW2lsjHT6B8Sh The top of my mitigation tube by my roofline was just a 90 elbow which allowed too much debris to fall down into the fan, eventually ruining it. Without this issue, I bet it would have kept running another 10 years. When I replaced this fan, I added an extra elbow joint so the top tube now it does a 180, which should solve that problem. The radon guys around here wanted to charge me a $300 diagnostic fee, then parts/labor (probably close to $600 total). I installed this all by myself in about an hour for the cost of the fan; it would probably be even easier/faster with two people. FYI the manufacturer's warranty greatly differs depending on whether you install it yourself (1 yr warranty) or have a licensed installer do it (10 yrs).

[@toddjasper1]

My man went from thinking he had a tankless setup to now a dual tank configuration

[@DaniilStanisevschi]

This is the most expensive & ridiculous "bolt on" solution I have ever seen. They would have been better off, cheaper, and more maintainable to rip out the "tankless" BS and put in a solid 7G+ / minute gas-powered tankless. A true tankless.

[@Egleu1]

They rarely need that capacity.

[@ryanroberts1104]

My favorite part is how you take an electric water heater and remove the element to call it a "storage tank", and the price goes up significantly.

[@hometownmedic7355]

@@Egleu1 If she isn't bathing 4 times a week after all that, he should divorce her immediately.

[@Engineer9736]

@@Egleu1 I was thinking the same while watching the video… The energy cost to keep all that hot water ready to go will rise through the roof, while wasting 98% of the produced heat by not using it.

[@JS.990]

Hes probably thinking to himself "All of this for a mf tub" 😂😂

[@peterjanis2455]

Women 🤣🤣

[@jamiemacdonald436]

@@peterjanis2455 Happy wife, happy life. 🙂

[@shanew7361]

As long as she's paying for it, I'm good.

[@squidboy0769]

Henry is good at rounding numbers.

[@Guillotines_For_Globalists]

His rounding is less than accurate for an asian engineer.

[@c0mputer]

At 8:17 Henry should have walked in with a towel wrapped around his waist and a shower cap, haha.

[@okyowwowoolala6384]

Pretty standard fix we do this all the time but with chillers when someone has oversized the equipment, it’s a less expensive fix then replacing the unit usually and usually trying to put a higher volume unit in could cause short cycling which reduces the units lifespan hence the holding tank.

[@kalijasin]

"Pretty standard fix we do this all the time" good reason not go tankless.

[@bboi]

@@kalijasin Tankless is great. This guy just needed a bigger unit or multiple normal sized ones to handle 7 GPM. Most Tankless heaters do 4 GPM just fine.

[@trustbuster23]

That poor guy got sold a bill of goods by his initial installer. Now he has this complicated system with extra sensors and pumps to basically just recreate what a simple, gas-fired water heater of the correct size could do. What do you think a standard boiler and a basic 80 gallon water heater would have originally cost vs. all of this? And I bet all those uninsulated pipes circulating the hot water between the small and large tanks means it is less energy efficient too. It sounds like a great idea, one boiler for both hot water and heat, but only if the system is properly sized for the expected demand.

[@peppeddu]

It's a dual use heater, hot water and radiators. A simple gas fired water heater wouldn't work in his case.

[@trustbuster23]

@@peppeddu My point was that he shouldn't have bought the dual use in the first place, because a basic hot water heater and basic boiler for the radiators would have been wildly cheaper, less complicated and more efficient. I get that this is probably the most cost-effective way to fix the current issue. But it is a problem that should never have happened in the first place.

[@shanew7361]

​@@trustbuster23 I was thinking the sane thing. The guy got ripped off lol

[@jesusnthedaisychain]

All of that work to go right back to having an overcomplicated hot water heater.

[@stephenc123]

It would have been nice to hear how much hot water the combi unit can put out by itself.

[@eXdXgXe4life]

It's not a water heater. Storage only.

[@johnlebzelter4208]

@@eXdXgXe4life right. Who asked @Captain Matticus for his opinion.

[@gpslightlock1422]

Cold water heater!

[@craigrulz8164]

Hahaha that’s awesome

[@jamesderynck1219]

Richard Needs his own Show

[@keithkareiva9615]

That is kind of the only solution. I had the same issue. I purchased my house with a large soaker tub and the house came with (2) 40 gallon traditional water heaters. That worked fine until they started leaking. I replaced them with a the largest tankless unit that I could find. (I believe that they are limited to 199,000 btu's due to some code constraints.) Well, the tankless worked great for the rest of the house, but it couldn't keep up with filling the tub. I live in northern Illinois, and the incoming water from the ground was around 50 -55F. The tankless can only raise that water 40 degrees at 9 gallons a minute, so in order to get a good 50-60 degree rise, the unit throttles down the flow. So it literally would take over a half hour to fill the tub. I ended up purchasing a 75 gallon traditional water heater to preheat the water, and then the tankless picks up the slack. I have to believe that there is a better solution to this problem; but I have yet to hear about it.

[@ZergZfTw]

Depending on what brand tankless you have, you can connect multiple in parallel, they have cables that let the units talk to each other so that they can share the load evenly. Most brands let you connect up to 4 units.

[@javiergalvan2604]

Another great and educational video! 😊❤👍👌🙏

[@allegory7638]

So all said and done, I'm better off with a tank type water heater.

[@hometownmedic7355]

Well it sure would save you a few bucks in copper, that's for sure.

[@ambee514]

Tankless is way overrated, an 80 gallon heat pump hybrid water heater is probably the best option on the market right now. 80 gallon capacity is practically unlimited hot water (unless you have like 5 people showering at the same time) and the heat pump gives you fractional operating cost over a traditional electric. Upfront cost is the biggest downside.

[@Charlesb88]

Maybe, maybe not. There are different advantages and disadvantages of tank, tankless, and hybrid units that depend on one's unique situation. In this persons case, a different choice when the hybrid unit was first install would have been better for them but. as it is, this add-on reserve tank resolves the issue at a lower cost then replacing the hybrid unit itself. Their new setup Isn't really as complicated as it looks on the surface.

[@carsonfiero4209]

The good old tanked tankless system.

[@ronevans852]

Nice video man doses he knows his pluming and hot water heater.

[@GarageWorx]

Pretty slick.

[@Ryansroga-wm6pj]

Pretty cool pretty cool

[@simonsonjh]

Very good explanation of the problem! How does the cold-hot mixing work when leaving the extra big storage tank? If mixing in cold, then less hot water is needed; therefore, I think the storage tank is much too large and wasting too much energy.

[@garretts91]

Why an 80 tank? Seems large for the demand. Any reason why you didn't add a 40 or 50 gallon tank?

[@zigman1976]

That hot storage tank alone is about $2000 part. Without the markup by the installer.

[@AnthonyCurreri]

I'm confused. Is the new tank just for the tub? Or does it service the entire home along with the original 20 gallon tank inside the boiler?

[@gpslightlock1422]

Yes! It was installed for the tub but it feeds the entire building. Mama fills the tub while dad's doing the dishes and everyone has hot water!

[@Anon-qc4ie]

Is this the same as a recirculating pump?

[@JonMasters]

I love how it just so happens to be Jim Papalia there to do the install. For those who don’t know, that company is huge in the greater Boston area. It’s not some dude. But he happened to be the guy 😂

[@jptrainor]

"Combi unit". It's a combination of over complicated and over priced.

[@DRugfree1987]

It’s a “combi” because is a boiler and a water heater.

[@red2516]

Is that a triangle tube boiler

[@Steve-bm2zm]

Should have bought a better combi boiler to begin with.

[@hometownmedic7355]

So a super fancy TANKLESS system with not one but two tanks to make it work? This is why I have trust issues.

[@hometownmedic7355]

Three. I commented before the expansion tank went in. Three tanks to go tankless…

[@buildingwhisper]

The original one was not sized according to the demands of the house. He has a huge bathtub. That's why they added the storage tank. And an expansion tank isn't to hold hot water, it's to prevent excessive pressure buildup due to the thermal expansion of water heating up.

[@e.nichols5380]

I have a rinnai propane true tankless that fills a tub just fine. Just have to get one big enough. Definitely cheaper than the route they went.

[@stevensalter9697]

They needed a 8gpm tankless they got the wrong one. It’s sad because they have this one hooked up to gas too! I’d opt for a new tankless properly sized.

[@ja8898]

Yeah they rate tankless heaters by their rise and their output per minute. If you get a bigger system with a higher rise and more output he wouldn't need all that.

[@PsycotikMind]

Would've been simpler to switch out the heater for one with a high enough BTU to keep up with the flow rate of the tub. Water is flowing too fast for the old one to work correctly.

[@Charlesb88]

Not really, They only need the higher flow of water for the tub only as everything else including showers work fine with the old unit. I imagine the coast is lower for a simple water storage tank, temp sensor, and pump unit then a whole new hybrid tankless water heater unit.

[@vwager]

My guess is the on demand hot water heater for 7.5 gallons per minute is probably more expensive than a storage tank.

[@PsycotikMind]

I said, "simpler". They might be saving some money, but adding a lot more fail points. And I did some Googling; the price of a fully tankless heater that could keep up with his needs is only slightly more.

[@kevinlucas8437]

There goes the $$$ heating that tank !!! For 24 / 7 for 1 bath a day !!!!😮

[@Todd_Kobell]

"sorry about the wet hand shake" Dying rn lol

[@GrahamDIY]

The cost of all that pressfit plumbing fixtures 😱

[@OscarPerez-uq7zt]

Now ur back to a tank water almost heater

[@TENTHIRTYONE]

I always call in a plumber to help me with my “dump loads”.

[@Guillotines_For_Globalists]

I drop loads nightly.

[@kalijasin]

Tankless no longer tankless. 🙈

[@chrisbrown456]

One thing I wish I could've learned was how !much a tank like that costs

[@jamiemacdonald436]

One that size is $2-3k before installation.

[@shanew7361]

With installation about $5k

[@rupe53]

@@jamiemacdonald436 ... ok, but he really didn't need the full 80 gallons because you can use a 40 gallon tank, then heat to 140 degrees and use a mixing valve to get 60 gallons to the tub at 104 degrees. (fairly hot bath) There are indirect fired tanks out there for $1500 - $2500 plus installation, which will recover faster than a gas water heater. Heck, I'm still using my 27 year old Amtrol Boilermate unit to fill my hot tub and that will use however many BTUs my boiler will crank out. (up to 190,000 BTUs) They still make a similar unit with a poly tank and the warranty is longer!

[@jamiemacdonald436]

@@rupe53 Not sure why this was directed to me. I was only answering their question.

[@rupe53]

@@jamiemacdonald436 .... not directly at you.... but replying to you will send the message to everyone in the thread.

[@JAMESHOUSTON-dn1im]

Richard is da man!

[@puwazatza]

matt risinger always raved about how great tankless was but this simple video proves what we should know about tankless setups.

[@phonedave]

There are tankless combi units and there are units like this with a small tank in them. Why somebody would get one like this is beyond me.

[@suspicionofdeceit]

This isnt a true on demand tankless unit, my Rinnai has no trouble filling a bathtub.

[@gpslightlock1422]

They did not account for the displacement of the person(s) in the tub. How many gallons is that man? They probably need 30-35 gallons of heated water.

[@terrorgen]

I would just add a 60Gal heat pump water heater just for the shower.

[@MustPassTruck]

Those restrictors are easy to replace.

[@miltoncallan1471]

Wouldn't it be cheaper to install an Insta Hot box in the wall?

[@kemmebudhai5160]

Lol this is the wife fault 🤣

[@stevensalter9697]

Now he has two tanks. Wat?!

[@Charlesb88]

Yes but one is much smaller and has a heater attached while the other simply stores extra heated water for the tub from the first. Having more than one hot water tank isn't that unusual in some very large house. This was likely the cheapest way to resolve the problem.

[@Mr-Chris]

What he needed was a stronger tankless that could keep up with the demand. This is just too complex.

[@phatboii0707]

I thought a tankless supply unlimited hot water ? So why doesnt the tub get hot water ? So confused

[@todd2456]

Tell me you didn't pay attention to the video without telling me you didn't pay any attention to the video.

[@alexchainey.]

Novel idea, take showers not baths. Cost $0.

[@DaniilStanisevschi]

Hold on a minute. A "tankless" was installed, but turns out it is a tank system with 20g onboard? What in the world, where is the efficiency. The unit is massive, I have seen smaller 7g/minute systems installed on gas-only connection. Second of all, what is the point of the massive "tank/tankless" when you're throwing a 80G stainless in there???? That thing is probably $2-5K and all of the pro-press fittings and copper are another $400-500. This job was probably quoted at $6-7K and Henry just wanted a hot tub?? Why, just why. I have a 1998 50G old-fashioned water heater that hasn't been drained or services besides a rod cleaning. I get hot showers, dishes and baths whenever. Unreal.

[@steve_main]

OMG that unit is a beast and can't keep up with 7.3 GPM?? I have one that is this little tiny unit that keeps up with my 15 GPM that i have for my 80 gallon Jacuzzi Watched to the end.. its not tankless is why and its a combo unit

[@bboi]

All this guy needed was 2 Rinnais to keep up with that heavy flow rate.

[@offroadrepairman]

Cheaper to go to a real tankless

[@berbagiilmudanpengalaman88]

👍🤝

[@timc1341]

So he now has both a tankless water heater and an 80 gallon tank water heater to provide 60 gallons of hot water. Makes perfect sense.

[@cmoreloon]

Should have just installed an indirect water heater and abandoned the internal indirect.

[@vwager]

This is the exact same thing I had in the 90s with my oil fired boiler ... it was called indirect hot water... apparently now if you buy an expensive on demand hot water heater it's now a reserve tank ... ok?!?!

[@rupe53]

Sooo, who takes a bath at 107+ degrees? That's really hot!

[@ilyafilru]

I have a tankless. It fills my tub just fine at 6gpm. Storage tank is inefficient.

[@Guillotines_For_Globalists]

So glad he got a tankless unit I'm sure. Progress!

[@shanew7361]

Why not just do a tankless for what that 80 gallon tank costs lol

[@ianbutler1983]

What a fiasco. A 50 gallon gas water heater would have worked just fine and be 1/3 the price.

[@RobertLeBlancPhoto]

Why can't he simply reduce the output of the tub filler to 2.5GPM once the first 20 gallons is put into the tub? Is there not a volume control on the tub filler? Sure, it'll take a few more minutes to fill the tub, but then he could avoid the cost of the added equipment, as well as the added energy costs to keep the indirect tank constantly heated.

[@dancooper6002]

Water cools too quickly

[@RobertLeBlancPhoto]

@@dancooper6002 I doubt the water would cool down that much in the 10 extra minutes it would take the fill the tub at a slower rate but hotter temperature.

[@B1gJ4k3]

Oh my god. Sooooo many more potential points of failure. When they wake up one day and don't have hot water, they've gotta check like 15 different things...

[@Mr.sassaman]

The timer was a video? Lmao

[@alimichelle6662]

MOST rich people stay rich by spending like the poor and investing without stopping then most poor people stay poor by spending like the rich yet not investing like the rich but impressing them

[@yaganabulama775]

She has really made a good name for herself, please any reachable means to expert Mrs Brenda Leigh Van.?

[@jimb8601]

Imagine spending all this money for a remodel and not going after the contractor for installing an inadequate hot water system. And then accepting the shortfall for 6 years.

[@dancooper6002]

Be your own contractor

[@beng3345]

Dude is a beta for living with this 6 years and letting the contractor do it this way originally

[@CortexGaming]

Put a flow restricter on the tub to only allow it to do 2.5 gpm

[@IFearlessINinja]

He said he tried a separate @2.5 but the water cooled by the time it filled

[@nilz23]

My wife wants to waste energy and water to take 60 gallon baths please help me!!!

[@cantcurecancer]

This is a solution for some crazy rich family who insists on taking 60 gallon hot baths because.... 'Merica For this owner's solution, I don't understand why they couldn't just turn up the temperature to solve the problem. They could have scalding hot water for the first 1/3 of the 60 gallon tub, but tepid warm water for the next 2/3, and I think it would balance out. That would come with the problem of scalding hot water throughout the home, but a little bit of training with the family members would solve that problem without the $5000 of work they just did. And if they couldn't turn up the reserve tank any higher (or if the reserve tank temp was controlled by the tankless temperature limit), then it just wasn't installed properly to begin with. For any other owner, why not just get a properly sized tankless and then add a recirculating pump? You get instant hot water with the pump (without scalding), and then the properly sized tankless will accommodate the tub and any other fixtures.

[@thomasreedy4751]

Crazy Rich family who wants to take baths????? You have no clue about their finances or physical mobility. Maybe his wife is an amputee and prefers to bathe in a tub. Hot water is not an overly expensive product and a bathtub isn’t unreasonable to me.

[@brianfong5711]

They cheaped out and got the bad tankless water heater that can't give 7.3 gallons per minute for 10 minutes continuously.

[@kalijasin]

Why not just upgrade the tankless to one more efficient and more gallons per minute instead of all this? 🤨

[@rupe53]

@@kalijasin ... because replacing that wall hung boiler with a larger unit would be $10k.

[@SpadeAce]

I have a tankless heater that cost me $180 and I get 140° hot water all throughout my house in under 30 seconds. I don’t know what heaters y’all are buying but you’re doing it wrong. This man went from a tankless to a combination to now having a tankless and a tank water heater. It’s backwards.

[@UMARWY]

He already got 20 gal of boiling water , I'd imagine thats enough for the tub since it'll be mixed with cold and definitely can fill that 60 gal

[@chrisbarnes2823]

I would have been way cheaper to install a 60 gal electric tank than install all the new modern stuff. Electricity is more efficient.

[@inodoroguerrero]

Electricity is more efficient, unfortunately in my state it is more than 4x the cost per BTU.

[@chrisbarnes2823]

@@inodoroguerrero I’m lucky I live in Ontario, Canada and we have lots of Hydroelectricity.

[@derrickraccoon7370]

@@chrisbarnes2823 your prime minister is a soyboy

[@tradermunky1998]

6 years!? That's a good woman, after 6 months most women are getting a lawyer.

[@TheOGize]

WHATS THE BEEF WITH KLEIN TOOLS ?!

[@joniboulware1436]

Can't wait til no more gas is allowed and we try heating water with electric for tubs. $$$$.

[@peterjanis2455]

Prioritize zone 4

[@jamedlock83]

7.317 doesn't round up to 7.5. . . LOL Dude needs to go back to school and learn how to round up/down

[@logik100.0]

The reality solution. Turn the flow down on the bath tub so the boiler can produce on demand what is needed, Tell the women to have a shower.Reality is the you spend $$$$ to heat the water up and all they do is sit in there for 5 mins.

[@rupe53]

If you paid attention to the video, the first thing he tried was filling the tub with the hand wand at 2.5 GPM. It took so long that the water cooled off already!

[@logik100.0]

@@rupe53 That was through the shower head that was restricted. If you open the tap slower than full blast then you can combine the instant heating and the tank. Also the shower head flow will lose more heat to the air than the tap flow. There is no rocket science in this, it's obvious stuff.

[@rupe53]

@@logik100.0 ... the problem with a boiler like this is it's only rated for around 3 GPM to get the temp rise for domestic water. That's why they have the internal tank. It's just enough for front loaded washers or a 10 minute shower.

[@tycox8704]

No doubt, the wife drained all that water after a single soak. Only in America. If soaking, rather than bathing, is the goal, install a hot tub.

[@tarashorts]

That is expensive we are path earn than this 🍎🍎🍎

[@ekujj13]

I’m surprised the new world order would allow this woman to use the energy and water to take a hot bath.

[@kennethandrysiak4130]

Huh… so they heat water ($$) and then mix it (downstairs… on the ‘hot water line, mind you)… and send it to all the water appliances. Pay to make hot water then cool it. Well, that certainly makes sense. Not.

[@caloy6981]

Sure. Have the Asian guy do the math 🙄😆😆😆

[@beng3345]

Dude is a beta for living with this 6 years and letting the contractor do it this way originally

[@warrendurham7358]

Unnecessary

[@brian-nz3jg]

What branch of the military ? Reserves ? Navy ? Marines? 😅

[@brian-nz3jg]

Tanks anyway for all you do 😅