How Hot Can It Go?! Can It Reach 70 degrees?! Vaillant Heat Pump Hot Water Cylinder Torture Test

[@UpsideDownFork]

Part 2 continues here : kzbin.info/www/bejne/bZzbi56DlNSXsMk

[@Crustyjugglers123]

We’re getting ours installed in a couple of weeks, looking forward to it! Your videos were really useful for us, thank you!

[@joewentworth7856]

It's a great piece of kit had ours for nearly 2 years and it's been a champ.

[@UpsideDownFork]

Congratulations! Hope everything goes well and feel free to continue to comment and add to the positive voices around heat pumps.

[@sowgroweat6987]

Love real world examples like this that gives us Solar noobs such great information

[@UpsideDownFork]

Thanks for your comment and feedback!

[@robinbennett5994]

I like the casual flex of doing all this on your solar power...

[@UpsideDownFork]

Haha 😂 unintended I promise you!

[@bordersw1239]

Thanks , would be good to see a comparison video for the depths of winter.

[@UpsideDownFork]

Remind me later in the year please!

[@effervescence5664]

The Vaillant can hit 70 but the refrigerant gas used isn't normally geared towards that top end = normally around 65c. The top of the tank will likely be higher, the benefit of higher storage temperatures is smaller tanks to give the same volume of mixed hot water allowing for more properties to actually fit heat pumps. Though they will cost more to run until other gasses come along with better operating ranges. While I am thinking about it, over 50c is classed as scolding hot water. Most TMV's / taps / shower valves are limited at 48c top end, majority are set some where between 38c and 46c.

[@UpsideDownFork]

👍 agree

[@jameswestcott4191]

Very helpful. Interested to see a re-run of the test at night or when it’s cold outside. Makes me lean towards having a separate hot water heat pump cylinder.

[@UpsideDownFork]

Please remind me when it's cooler and I'll re-run the test for you. Why are you leaning towards a separate cylinder?

[@Group51]

With my SunAmp Heat Battery, my Vaillant has no choice but to hot its water to 70c each day. Hysterisis or bust! I don’t have road noise in my garden. Still very quiet in operation. And your Vailant graph looks identical to mine!

[@givemethejob3293]

As the sunamp stores no water only heat in the battery, why does it need to heat to 70c? Surely 40c would be fine maybe a sterilisation cycle occasionally?

[@UpsideDownFork]

That's interesting that you have no other control over the sunamp. I'd be interested to know why that is, either a technical reason or a strategic choice by them?

[@Group51]

@@UpsideDownFork I think it’s the melting point of the phase change material. But I really don’t know. As it can sort of trickle charge from an Eddi. But installed early summer I never saw the Eddi do that really. It always went straight to 3Kw from my excess solar.

[@Group51]

I didn’t want the Eddi installed. It just came with the SunAmp and the installer didn’t want to install direct to the SunSynk AUX instead (as a backup). Eddi felt like and still feels redundant.

[@MrStraightdart]

The fact the flow temperature hit 70 on the app shows it can hit 70 no problem

[@Andrew-ht2zi]

Very helpful. It would be cool to see the time and energy taken using only the immersion for comparison

[@UpsideDownFork]

Thanks for the idea! A follow up video is on the way already.

[@Bandits_At_3_o_Clock]

Thanks for the video. Just like anything else if it's been installed properly then there won't be a problem. Have you relocated the ASHP to the left a bit?

[@UpsideDownFork]

@@Bandits_At_3_o_Clock yes, the HP has been shifted to the left 👍

[@robvtrickey]

We have the Vaillant 7kw model, plus a newark HG 250L cylinder. Our legionella cycle (no immersion) usually gets the cylinder up to about 68.5° at a COP of 3.2.

[@Aphova]

That's great. What's your COP on that cylinder at lower temperatures if I may ask? I'm looking at getting one myself.

[@robvtrickey]

@@Aphova We've only had it a few weeks, but in these hot temperatures, to heat up to 45, it's been getting over 5 every day. Hit 5.5 on one day.

[@UpsideDownFork]

Good to hear! I'm envious of the coil size in your HG cylinder!

[@UFZ7482]

Good vid, I wonder if are you pushing the limits of the physics of a propane refrigerant? in other words thermodynamics won't let you go higher?

[@UpsideDownFork]

Most of the R290 heat pumps advertise a 75 degree flow capability. Another commenter has found the reason for my failed attempt and I'll be posting an update video to explain what went wrong and why.

[@RussMBrooks]

The top third of the tank would probably be at 70c.

[@UpsideDownFork]

Definitely!

[@rowanballinger3690]

Why the hell would anybody want water above 60°? All you’re gonna do is mix it with cold and blend it back down again you’re wasting energy.

[@steve_787]

It'll be the same people that claim they need a range of 600+ miles in an EV other wise it's pointless and not worth it 😉

[@asabriggs6426]

If your hot water tank has been undersized or you have an unusually large number of people around then you may need that extra hot water capacity.

[@johnzach2057]

It can have some benefits. If you have many guests arriving you need the most DHW you can have and the easiest way is to increase the temperature of DHW. But you can do that even with an immersion heater for cheap. So there is zero practical benefit from using a 60°C HP vs a 70°C capable HP.

[@UpsideDownFork]

Good community engagement here!

[@rednammoc]

One more possible reason is that the hot water pipe to the kitchen taps is somewhat long and (in my case) very poorly lagged, or somehow in close proximity/direct contact with a mains cold water pipe and is buried in solid concrete floor. The extra heat offsets the inefficiency to yield sufficiently hot water at the sink.

[@serraios1989]

With a thermostatic mixing valve it is possible to increase the amount of usable hot water at a comfortable temperature, eliminating the risk of scalding and minimising waste of hot water. The cylinder can be heated to 60-62 degrees and have the valve set at 43 degrees. It is fitted directly after the cylinder and mixes hot and cold water from the mains at the set temperature. Installation is simple and the price is very affordable

[@_Dougaldog]

Ideally HWC should be correctly sized so that it only needs to heat to 43C, giving best performance all round.

[@serraios1989]

@@_Dougaldog Agreed. The thermostatic mixing valve could be an option if the cylinder is undersized for whatever reason, cylinder reheating time is too long and the cost to charge the cylinder is reduced during the night on cheap electricity tariffs

[@UpsideDownFork]

This is good advice for those situations!

[@joewentworth7856]

It may have to do with you water temp offset. I think its set to 5k default . So to get 65water it needs 70 running in the coil. You can adjust it on the vailant wall unit. Perhaps in the installer section. But as you say what do you need 65 plus water for?

[@UpsideDownFork]

Mine was set to 2k, but another commenter has found the reason and I'll be posting an update video to explain what went wrong and why.

[@pmbpmb5416]

Speak to the geek 🙂

[@UpsideDownFork]

He has some great content!

[@edc1569]

Probably a bit different doing this in sub zero outside temperatures when you also need to space heat. Though with the right sized cylinder and heat pump you are going to have plenty of hot enough water.

[@UpsideDownFork]

I don't notice much difference in the reheat speed between winter/summer but that may be down to my HP being oversized and cylinder being undersized.

[@davideyres955]

⁠@@UpsideDownForkit’s not that they cannot do it, it’s the energy efficiency drops in the winter. Real world example like this are great though should help to put people straight.

[@UpsideDownFork]

@@davideyres955 the difference for me has been between 1.5kWh electrical input required on a warm day and 2.5kWh required on a cold day. The difference is so much smaller than I expected. We also use more hot water in the colder months.

[@johnzach2057]

How hot is the water leaving the heat pump? Because this looks to me like losses in the system. If the water reaches the water cylinder at 65 °C then the DHW will only reach 65 °C or less.

[@UpsideDownFork]

The highest I've witnessed from the HP is 70 degrees but I'm led to believe it will exceed 75 degrees. Another commenter has found the reason and I'll be posting an update video to explain what went wrong and why.

[@h.e.verheijden8083]

30 degrees outside!

[@MacCraig8]

The bottleneck here is the coil in the cylinder though, not the outdoor temp. 70 flow is reachable regardless of weather but if you actually want water in the cylinder close to that (for bizzare reasons) it's going to slow down the heat transfer regardless of outdoor conditions. Heats to a perfect usable hot water temp any time of year easily.

[@MikeGleesonazelectrics]

That is correct, it just takes a bit longer to get up to temp.. I've been using heat geek mode on my vaillant water cylinder set t 45C minimum flow temp.. working great, extremely efficient!

[@UpsideDownFork]

Yep, too hot for me!

[@ricardopelc-wesoly3483]

But I wanted a hot bath an hour ago!

[@UpsideDownFork]

Ha, always the way!! If you fail to prepare, you prepare to fail!

[@Biggest-dh1vr]

You may want/be able to do more hiding of your physical mobile screen for privacy? [Edit: fixed boring to hiding]

[@UpsideDownFork]

Yikes. What have I missed 🤔

[@Biggest-dh1vr]

​@@UpsideDownForkfrom about 0:30 your Arotherm details are blocked on the left, but perhaps visible and blurry on the right. Not sure how sensitive the details are.

[@ecoterrorist1402]

i noticed that you have moved the Heat pump then? Now you have done the test at an outdoor temperature of 28 degrees, can you repeat the test at -5 degrees?

[@_Dougaldog]

What difference would you expect to see at -5, given that most UK heat pumps will work to -25C ?

[@ecoterrorist1402]

@@_DougaldogSearch for ASHP COP efficiency versus temperature charts to understand the age-old tale: you can't get something from nothing..

[@_Dougaldog]

@@ecoterrorist1402 So what would You expect to see at -5, genuine question ?

[@ecoterrorist1402]

@@_Dougaldog The cost to operate the heat pump would involve a coefficient of performance (COP) of approximately 1.5 to 2 at -5 degrees, compared to a COP of 5 at 30 degrees.

[@MentalLentil-ev9jr]

@@ecoterrorist1402 You've got that wrong according to the Vailant manual. The COP of the unit varies according to the flow temperature, not the outside temperature, so the COP will stay the same. What will happen at lower outside temperatures is that the heat pump will not be able to generate as high a maximum power, which may or may not cause problems as the tank may take longer to heat up. In case you're wondering why then does the COP for heating a house drop when the outside temperature is lower, that's because a lower outside temperature requires a higher flow temperature through the radiators to keep the house warm, it's not the outside temperature effect on the heat pump that causes this. Of course in colder weather the water inlet temperature to the tank may drop a little, this will increase the energy input but will in fact raise the COP because of the lower flow temperature for that part of the heating cycle. For reference: the Vailant Arotherm manual quotes a COP of 3.39 at 55°C for a 7kW version whether the temperature -5°C or 2°C, the output though changes from 7kW to 8.5kW.

[@chriscandlish8215]

I thought you set DHW temp to 65, then you increased it to 70?? It seems your 65 was reached, but you seem to have increased the required temp to 70. Heat pump will only start a cycle again if hysteresis allows. I have 7kw Arotherm plus, which can reach tank temp of 70 deg ok with the 90 mins cycle time - I tried it to check. Note also the DHW settings for Normal Balanced, or eco, which will affect how the compressor runs.. Normall I use a DHW temp of 55, which allows enough hot water for us in one charge. If you need more volume of hot water, then use a slightly higher DHW temp in the tank. Efficiency or more importantly power consumed is not greatly affected. COP will only reduce a bit at end of cycle when higher temp is needed. Energy used is the important factor. Also note that outside temp affects COP, so people comparing COP and energy use should reference outside temp. Up here in Scotland our os temp is normally lower than down south so will get lower SCOP. Hope this helps..

[@UpsideDownFork]

You win! kzbin.info/www/bejne/bZzbi56DlNSXsMk As soon as I read your comment, the penny dropped. I unwittingly sabotaged my own test by upping the temp and forgetting about the hysteresis! Do you have a 250L cylinder?

[@chriscandlish8215]

​@@UpsideDownFork- glad to help. You are being really helpful by getting to grips with the operation of these units. I have a 300l tank which is a bespoke unit sized for a water source heat pump - which I had to replace with an air source unit. I have tried several things to try and improve DHW COP, but they are all marginal. Biggest factor seems to be outside air temp. I run an occasional 70 deg cycle as we are on our own well water source., so know the unit runs up to that temp ok. My Heating SCOP of 4.6 is better, UFH and good insulation running at a 0.25 heat curve... My unit's performance seems to match Vaillant's performance curves for these units so really happy with it... .

[@UpsideDownFork]

@@chriscandlish8215 That all sounds good! How frequently do you heat the cylinder? How low does the temperature get before you start a reheat cycle? In addition to the factors you mention, i've found that the start temperature can make a significant difference. Do you know how large the coil is in your cylinder?

[@chriscandlish8215]

​It's all quite interesting stuff.. I have a timed DHW period from 9 - 5 so I can use solar if any available. It normally does one cycle at 9am. I have a solar iboost that helps top up in summer - I use this rather than link the ASHP as the solar power can come and go depending on clouds 😂😂. No battery as investment pay back didn't work for me. Lowest temp normally about 45 at time of recharge, currently use 55 set point with 7 degree hysteresis. Was using 50 but decided to have higher 55 as its an unchlorinated well source (uv treatment). With occasional 70 disinfection. Probe location is 2/3 up tank, below iboost immersion though. Put it on manual when family staying as we then use 2 times the hot water... Unfortunately don't know coil size as bespoke unit serial number missing and tempest can't tell me. But it works fine. I had to reduce heat pump DHW pump speed as it was rattling the coil😂😂. That increased the flow /return delta t to 7 deg from 5 deg, with same charging time so same heat transfer, no apparent change in COP. I think coil size is about getting a full tank of hot water, and charging time, not sure it affects the COP at all - that seems to be governed at the ASHP it's flow and return temps, outside air temp, and compressor speed. Looking forward to seeing more interesting stuff....

[@MrStraightdart]

Need to go in to installer settings and set max temps. Your system has hit max setting it will easily do 70 with the correct settings

[@UpsideDownFork]

Max temp is only relevant for the CH side of things but another commenter has found the reason and I'll be posting an update video to explain what went wrong and why.

[@MrStraightdart]

@@UpsideDownFork sorry but that’s not correct I’m an installer and everything you can set in heating you can set in hot water. My point was a setting wasn’t set correctly to get to 70. One of the things I find frustrating with vaillant is the terms they use for various settings. Keep up the good work 👍

[@UpsideDownFork]

@@MrStraightdart I've just check on both my sensocomfort and the white interface and can't find any max temp settings for hot water. Could you direct me which setting I should be looking for?

[@MrStraightdart]

They are in the installer level settings. You’ll need the codes. I’m sure you can find the codes I don’t mind sending you the standard codes unless your installer changed them but don’t think I should put them here as people shouldn’t fiddle with the settings without knowing what effect they can have

[@UpsideDownFork]

@@MrStraightdart yes, I have the installer codes and have been in those settings menus many times. Should I be looking in the sensocomfort or the hard wired interface?