A booboo may have been made

[Post and beam]

I just had a google of TMV.  i do not have one of these as far as i can see anywhere.

[HughF]

9 minutes ago, Post and beam said:

I just had a google of TMV.  i do not have one of these as far as i can see anywhere.

post pictures of your UFH manifold, please.

[JohnMo]

2 hours ago, Post and beam said:

But, the fact remains, i asked for a 2 zone installation with control of each independently. 

But is your installer saving you from yourself? He is wanting a good performance system as well installers should. If you had asked for a thermostat in every room, he may not of done that either.

[Post and beam]

18 minutes ago, JohnMo said:

But is your installer saving you from yourself?

How so ?

 

18 minutes ago, JohnMo said:

If you had asked for a thermostat in every room, he may not of done that either.

I have had potential installers design for and offer  that and i rejected them because its a stupid idea.

[Post and beam]

2 hours ago, HughF said:

post pictures of your UFH manifold, please.

Will do once i get home

[JohnMo]

1 hour ago, Post and beam said:

potential installers design for and offer  that and i rejected them because its a stupid idea.

2 zone is just a little different from multiple zones. Read into that what you want.

 

1 hour ago, Post and beam said:

How so ?

Read above 

[SimonD]

Have you not received a design from the installer? You probably have got the weather comp curve set too high and should have been told by your installer that it takes a while to set the system up properly. Has the installer arranged follow up visits to balance the system when it gets colder?

 

What we really need to know is what mean water to air temperature difference the radiators have been specified to. That way we can tell if there needs to be a flow temperature differential between the radiators and ufh.

 

In 2025, a 2 zone system with rads and ufh needs to have an electronic mixer to properly deal with weather and load compensation within the heatpump and both the zones.

[HughF]

15 minutes ago, SimonD said:

 

In 2025, a 2 zone system with rads and ufh needs to have an electronic mixer to properly deal with weather and load compensation within the heatpump and both the zones.

Good luck getting that from any of the big heat pump installers.. Even the Vaillant big-book-of-schematics doesn't show any electronically mixed circuits, and Vaillant are often considered a premium product.

[SimonD]

33 minutes ago, HughF said:

Good luck getting that from any of the big heat pump installers.. Even the Vaillant big-book-of-schematics doesn't show any electronically mixed circuits, and Vaillant are often considered a premium product.

 

But they have them on the wall in their training centres and sell single and dual valve insulated esbe kit. The schematics and wiring diagrams are available.

 

3 mixers are supported by vr71 connectors r7 through r12

 

But as you say, not many seem to rtfm, or pay attention during their training, if they've been to it at all? And you're unlikely to get this from many of the big installers I suppose?

 

It's weird they don't make it more obvious.. 

 

Grant on the other hand provide an installation kit for the aerona 290 that includes an electronic mixer for combined ufh & radiator circuits and the schematics and wiring diagrams are 1 of the standard one in the manual. What a comparison...

Edited Tuesday at 14:24 by SimonD

[HughF]

20 minutes ago, SimonD said:

 

But they have them on the wall in their training centres and sell single and dual valve insulated esbe kit. The schematics and wiring diagrams are available.

 

3 mixers are supported by vr71 connectors r7 through r12

 

But as you say, not many seem to rtfm, or pay attention during their training, if they've been to it at all? And you're unlikely to get this from many of the big installers I suppose?

 

It's weird they don't make it more obvious.. 

 

Grant on the other hand provide an installation kit for the aerona 290 that includes an electronic mixer for combined ufh & radiator circuits and the schematics and wiring diagrams are 1 of the standard one in the manual. What a comparison...

It could be that my book of schematics is out of date, but I did find it annoying and slightly weird that the standard single zone, no buffer, single pump schematic was on page 75 of 99...

 

Just looking at the Grant handbook now, nice to see such simple and well explained schematics.

Edited Tuesday at 14:37 by HughF

[sharpener]

On 17/10/2025 at 17:09, Post and beam said:

Memory fails me dude. Would you point me in the right direction please

 

Vaillant schematics files are here.  Ask you installer to show you which one he has used, and what the features are that give independent control of the two zones, and where the VR70 wiring centre and second temp sensor have been installed.

 

6 hours ago, Post and beam said:

What is the TMV, i think i can guess but not aware of it what it looks like or where it might be.

 

Temperature Modulating Valve. It will be a valve with 3 pipes near the manifold/pump for the UFH, and probably have a coloured top - to adjust the URHF feed temp to a lower value than the rads need.

[Post and beam]

[Post and beam]

The yellow vertical pipes come from the Ashp up through the slab and go left and up to the UVC. They are 28mm. On the manifold picture the 2 pipes come from the UVC area upstairs, they are 22mm. No TMV .

[Nickfromwales]

1 hour ago, Post and beam said:

The yellow vertical pipes come from the Ashp up through the slab and go left and up to the UVC. They are 28mm. On the manifold picture the 2 pipes come from the UVC area upstairs, they are 22mm. No TMV .

Thanks for the pics. 
 

So you have a single CH flow temp, and no differentiation between UFH requirements and those of the rads. 
 

Not a great setup afaic, so I’m not surprised it’s not ‘doing exactly as it says on the tin’.

[Post and beam]

Exactly. Hence my question to my installer. I dont believe they have delivered what i asked for.   As it happens, and totally unsolicited the MCS  guys have asked if they can audit my install. 

[Post and beam]

52 minutes ago, Nickfromwales said:

 

So you have a single CH flow temp, and no differentiation between UFH requirements and those of the rads. 

Hi @Nick ? Can i recover this to an acceptable solution without major surgery?   

[Nickfromwales]

11 hours ago, Post and beam said:

Hi @Nick ? Can i recover this to an acceptable solution without major surgery?   

The quickest route is to just add a TMV and pump to the UFH manifold, and raise the CH flow temp of the ASHP. 
 

I doubt you have enough wiggle room to just slow the UFH flow rates down, but it is a possibility; but then you’d need to dial the CH flow temp up by max 2-3° to see if the rads perk up a bit.

 

This will be quite coarse, and as TRV’s operate the balance will shift as it’s all hydraulically interconnected; water flow will just go to the path of least resistance, so that’ll prob be the shortest UFH loop or the first rad that it ‘sees’. 
 

Ultimately, I think it’s time you called the installers back, sit them down, and lay all this out in front of them, as atm you’ve not got a system fit for purpose and a wedge missing from your bank account for the (dis)pleasure.

[Post and beam]

Thanks Nick. I think i have enough space to install a TMV  to the 22mm pipe pairs.

As an aside my flow & return temps gauges show 25c and 22c, so a Delta T of just 3 degrees.

 

Still waiting to hear from my installer. I am about to become mister angry customer.

[SimonD]

48 minutes ago, Nickfromwales said:

The quickest route is to just add a TMV and pump to the UFH manifold, and raise the CH flow temp of the ASHP.

 

21 minutes ago, Post and beam said:

Thanks Nick. I think i have enough space to install a TMV  to the 22mm pipe pairs.

As an aside my flow & return temps gauges show 25c and 22c, so a Delta T of just 3 degrees.

 

Still waiting to hear from my installer. I am about to become mister angry customer.

 

I seriously suggest you ask (instruct them in no uncertain terms) your installer to install one of these as it provides weather compensation across different zones. As standard tmv & pump arrangement won't do that and will essentially have relay control.

 

https://professional.vaillant.co.uk/for-installers/products/vaillant-mixing-module-vdm-69824.html

 

Given your installer doesn't appear to understand open loop, even if they think they do, you might want to suggest they contact Vaillant to get the schematic for this system and make proper adjustments.

[HughF]

What brand of heat pump?

[Post and beam]

26 minutes ago, HughF said:

What brand of heat pump?

Vaillant Arotherm 5kw. 2 months old. one week since moving in.

[HughF]

You've got a couple of options:

 

1. Fit a dumb pumped manifold to the UFH, hydraulically decoupled from the radiator flow and return using close-coupled T's (this is what I use). Then increase the flow temp so the upstairs rads feel warm.

 

2. Fit a Vaillant mixing station to provide a mixed circuit independent of the radiators.

 

3. Upsize the rads in the upstairs rooms to suit the fixed flow temp of the UFH.

 

In relation to option 3, do you know if the rads were sized for 35 degree flow?

[JohnMo]

1 hour ago, Post and beam said:

one week since moving in.

So how are room temps now in the house and using house proper?

 

Do you run all the time or do you switch on off at different times of the day?

[Nickfromwales]

I doubt there’s much point in attempting to make the 2 circuits independent, as the TRV’s will provide simple, effective control to each space with a radiator, whilst the system ticks over to the UFH in the background; so basically your entire heating system is ‘on or off’. 
 

The issue is, if you have a room stat downstairs there is a risk of that switching the heating off sporadically, starving the rads of flow and the sections of heat input.

 

Theres a lot of info to be exchanged for us to fully grasp / offer a robust solution, but as above, get these guys back and make it their problem. 
 

The caveat is, they may be at max capability already, hence the crappy solution they left you with, so you may need to escalate this if they can’t step up to the plate.

[Post and beam]

4 minutes ago, Nickfromwales said:

The issue is, if you have a room stat downstairs there is a risk of that switching the heating off sporadically, starving the rads of flow and the sections of heat input.

Room stat is wired and downstairs, my choice to have it hardwired, possibly not one of my finest. 

The UFH actually heats the ground floor very well and therefore does indeed switch off at desired temp. As previously mentioned. The manifold temps this morning at 7 when it was heating were 25c flow & 22c return. ( analogue gauges on the pipework)

The 35c i mentioned was the highest i hoped it would need to run at for efficiency sake and not a set temp. It looks like it does not even need to run  that high yet.

For info the WC curve is .4