Notifications
Clear all
Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!
Domestic Hot Water & Cylinders
32
Posts
5
Users
19
Reactions
2,138
Views
Topic starter
29/01/2026 10:38 pm
Hi,
Yes it's a big new house 2022, grand design ish. Probably almost passivhaus standard, EPC A 99.. So there's a circulation pump as well going on.
Mike
1
29/01/2026 11:03 pm
@errmm, I suspected as much. This is high-end, expensive kit, so an installer shrugging and saying ‘this is how it just is’ is frankly enormous BS. Systems at this level should not be running out of usable hot water after a couple of showers.
It would really help to see more photos of the plant room, as @jamespa suggested, because on the face of it something is seriously wrong here.
Get a copy of The Ultimate Guide to Heat Pumps
Subscribe and follow our YouTube channel!
30/01/2026 5:22 pm
@errmm, I reached out to the distributors of Heliotherm in the UK to get more insights and they have informed me that they are now in touch with you and "on the case". Please let us know what they say.
Get a copy of The Ultimate Guide to Heat Pumps
Subscribe and follow our YouTube channel!
31/01/2026 2:29 pm
Attached are a few photos I took from today. I also have a video if that might help.
As you now have a Heliotherm engineer on the case I wont comment further. As @mars says this is high end stuff, the suppliers need to be made to work for their money!
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
1
31/01/2026 5:02 pm
@jamespa I'm still very curious why the installer said "this is how it just is"! Quite the statement that given the kit they've fitted.
I'm not sure I'll get an update from the UK distributors of Heliotherm on this, so would appreciate an update from @errmm when changes and tweaks have been made.
This post was modified 4 months ago by Mars
Get a copy of The Ultimate Guide to Heat Pumps
Subscribe and follow our YouTube channel!
1
06/02/2026 5:59 pm
@errmm, curious to see if there have been any updates on this project. Please let us know.
Get a copy of The Ultimate Guide to Heat Pumps
Subscribe and follow our YouTube channel!
Topic starter
07/02/2026 1:23 am
Hi,
Nothing yet. I've asked customer to measure flow and asked Heliotherm to explain exactly what that other cylinder does because it suggests instant hot water. Hopefully I'll have more information in a few days time.
1
07/02/2026 9:30 am
@errmm, have the original installers not come out to have a look and find the issue?
Get a copy of The Ultimate Guide to Heat Pumps
Subscribe and follow our YouTube channel!
Topic starter
09/02/2026 12:13 am
Hi,
No, we're currently in a situation where there isn't a confirmation that there is actually a problem.
I've asked the installer to explain exactly what that other cylinder does because from what I can see on the brochure it says instant hot water... The problem is I'm not sure there are any sensors on it so can't really see it functioning.
The installer is 80+ miles away from the customer so it's not a quick pop over and take a look.
09/02/2026 11:09 am
No, we're currently in a situation where there isn't a confirmation that there is actually a problem.
I think we can safely assume that with what has been described there is an issue 🤔
Has the system been commissioned and handed over to the homeowner?
Get a copy of The Ultimate Guide to Heat Pumps
Subscribe and follow our YouTube channel!
Topic starter
11/02/2026 2:46 am
House was finished several years ago, complicated a bit because home build was impacted by covid. Still waiting for reply from them on what the DHW cylinder does for the customer.
Latest Posts
-
RE: Cooling with air to water heat pumps
@springswood The most flexible and cost effective wa...
By Papahuhu , 8 minutes ago
-
Nobody will, that's the point of this thread, the heat ...
By JamesPa , 56 minutes ago
-
RE: Indevolt Batteries UK Support & Info Thread
Good morning. I just came across your website. Was ho...
By iRadiate , 5 hours ago
-
RE: GivEnergy inverter tripping due to over-voltage?
Many thanks for the helpful and educational inputs! I...
By Tim441 , 13 hours ago
-
RE: Failed Heat Pump Install: IWA Claim Rejected
Many of the estimates we received mention IWA and RECC....
By Batpred , 16 hours ago
-
RE: Rural burning – I've had enough
Same here in Finland. It's strictly forbidden ...
By upnorthandpersonal , 16 hours ago
-
RE: Renewables & Heat Pumps in the News
Something worth flagging... we've just published a news...
By Mars , 17 hours ago
-
RE: Renewable Heating Hub Homeowners' Q&A Podcast
The Homeowners' Q&A podcast is back... I've changed...
By Mars , 17 hours ago
-
RE: Anyone concerned about GivEnergy?
I have already signed up with Axle so yes, that takes c...
By KevH , 19 hours ago
-
@batpred Would it pass the airbnb feedback test no. I...
By EtchedPixels , 1 day ago
-
A quick update... we've just launched the beta version ...
By Mars , 2 days ago
-
RE: Who Actually Owns a Heat Pump in Britain? We Asked. Here Is What We Found.
The age part doesn't surprise me - only 25% of UK home ...
By EtchedPixels , 2 days ago
-
RE: Home automation and the cloud; is there a better way?
Nothing you've said there, @etchedpixels, is something ...
By Majordennisbloodnok , 2 days ago
-
I've heard from others living in the vicinity of Derril...
By Transparent , 2 days ago
