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Help me keep the faith with my air source heat pump installation

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(@ashp-bobba)
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Joined: 8 months ago
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@jamespa Hi James, I missed one essential thing with all that, I should of added the way round this is to alway fit a sub board already stocked with a RCD Type B and then cary all of the RCBO C type that are 16, 20, 32 amps all in the same make such as FuseBox for example only "not sponsored" that way the only thing you need to find on the shelf is the AAB old normal MCB thats a higher rating then the RCD in the new sub box to feed it or take the power straight from an existing splitter.

I agree with everything you say above fitting the correct fuse to the correct manufacturer, I just forgot to mention what I meant by stock the solution for all ASHP's is stock ready made sub boxes with the correct Type 2's already in. 

Also thanks for the support on the balancing of views, you are correct that most people with good installs are just getting on in life 🙂

 

 

 

Professional installer. Book a one-to-one consultation for pre- and post-installation advice, troubleshooting and system optimisation.


   
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(@adamk)
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Posts: 82
Topic starter  

@editor here's some pics.

PXL 20250627 160529206

 

One is a straight Flexi that has been bent twice and presses against the wall. The other is a straight with a built in hard 90 on the end.

PXL 20250702 214547838

This is my external CU.

PXL 20250718 094058677.MP

This is one from the heat pump training centre where I work. Tom Baines at Vaillant who I'm dealing with has seen the these 2 pics and the college one is correct, mine is not.

 


   
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(@adamk)
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PXL 20250627 160634715

Another angle. The pipes are bending and the insulation is being crush on one of the wall brackets.


   
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(@adamk)
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@editor actually looking at the college pic and my pic unless the surge protector is in the RCD, they won't be able to fix my problem as it would need a 7 way board.


   
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(@jamespa)
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Joined: 2 years ago
Posts: 2677
 

Posted by: @adamk

@editor actually looking at the college pic and my pic unless the surge protector is in the RCD, they won't be able to fix my problem as it would need a 7 way board.

They could hang a secondary CU off the existing ASHP MCB and then put the RCD in that - as @ashp-bobba suggests above I believe.

They may argue that its wiring-regs compliant as it is (which I think is the case) albeit that its not compliant with Vaillant instructions.  

As it happens I was quite happy for my electrician to do something similar for essentially the same reason (insufficient space in the CU for an RCD, no RCD and no RCBO available to fit).  My CU will be replaced anyway within a few years when I change the gas hob to electric (which will be when I redo the worktops) and get a bidirectional EV charger, at which point I will run out of options to fit any more into the existing CU.  However I concede its not best practice so Im neither advocating nor defending it; I just hate to use more materials than are needed if I know they will be thrown away before the end of their useful life.

 

This post was modified 1 day ago 7 times by JamesPa

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.


   
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(@ashp-bobba)
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Joined: 8 months ago
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@adamk You need this 

https://www.fusebox.shop/products/f3004rb?_pos=5&_sid=7d50518e8&_ss=r

or at least this if you have enough ways:

https://www.fusebox.shop/products/rtb630302m?_pos=1&_sid=5a8e6fb08&_ss=r

Professional installer. Book a one-to-one consultation for pre- and post-installation advice, troubleshooting and system optimisation.


   
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(@adamk)
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@ashp-bobba i would need an ip rated one as mines outside next to the meter box as it was the easiest way to power the HP from the Henley blocks. otherwise they would have used up the spare space in my new CU and had to try and run the cables from the middle of the house to the side then to the back of the house.


   
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(@ashp-bobba)
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Joined: 8 months ago
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@adamk Ah ok you can place the same RCD and breaker in an IP65 box

Professional installer. Book a one-to-one consultation for pre- and post-installation advice, troubleshooting and system optimisation.


   
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(@jamespa)
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So in summary it was a decision between pragmatism and strict conformance to what Vaillant say, even though (I believe) the latter goes beyond the requirements of the IET regs. 

Definitely scope for disagreement here, but personally I would happily accept pragmatism!  Others may quite strongly disagree.

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.


   
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(@adamk)
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@jamespa i just want it right at the end of the day, the fact that both whoever installed the test rigs at the college where i work and Vaillant both have used the correct kit says my installer is either not bothered or didnt realise. it could be because they use a separate electrical contractor that isnt technically part of the company and maybe doesnt know they are installing the wrong kit. to be honest if i hadnt been pinged by the FB algorithms the post regarding the difficulty getting the RCDs i wouldnt have known.

also now Vaillant know the wrong rcds mcbs are installed where do i stand on warranty?


   
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Mars
 Mars
(@editor)
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Joined: 4 years ago
Posts: 3376
 

Posted by: @adamk

also now Vaillant know the wrong rcds mcbs are installed where do i stand on warranty?

That’s an excellent question, and one I would ask Vaillant immediately and get a reply in writing, highlighting the install was from a Vaillant-accredited installer. That gives you an instant reply on how to act.

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(@jamespa)
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Posted by: @adamk

just want it right at the end of the day, 

Then that is what you should ask for.  As I say above Im neither condoning nor defending having only an MCB not a type B RCD plus an MCB (or an RCBO), merely stating that, to the best of my knowledge its not a requirement of the electrical regulations and it happened to suit me, for my house, which is (or should be) my choice. 

Im not an installer; if I were I would do what it says in the instructions or, if there were a very good reason not to in a particular case, give the householder the option making clear the risks and rationale.

That said, I have just checked my copy of the Vaillant installation manual (serial number ending _03), and the actual words there are 'To protect people' [type B RCDs] 'must be used if these are stipulated for the installation site'  (my italics). 

Since your installer has not fitted an RCD at all, he could reasonably argue that the IET regs don't stipulate RCDs, and what he has done (which does not include any RCD) is therefore compliant both with the regs and the Vaillant instructions.

Posted by: @adamk

it could be because they use a separate electrical contractor that isnt technically part of the company and maybe doesnt know they are installing the wrong kit.

Quite possibly.

Posted by: @adamk

i would need an ip rated one as mines outside next to the meter box

As a matter of interest, did they install the one you show in your picture, or was it already present.  I ask out of curiosity because, if they did, its more difficult to fathom why they didn't do what it says in the instructions.

Im also intrigued by the presence of a surge protection device in your installation, which, interestingly, doesn't feature in your college rig.  I dont know what it says in the Vaillant instructions, but the wiring regs would trump the Vaillant instructions if they require an SPD.  The IET (who are the authors of the wiring regulations applicable in the UK) has something to say about SPDs here but its open to interpretation either way IMHO, as is frequently the case with the electrical regs which are written with the assumption that the electrician is a professional capable of sensible judgement.

 

This post was modified 14 hours ago 11 times by JamesPa
This post was modified 11 hours ago 9 times by JamesPa

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.


   
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