Gas boiler lobby obstructing heatpumps

[DanDee]

8 hours ago, JamesPa said:

Now we need the manufacturers of HT heat pumps on board.  Daikin for example specify a min coil area of 1.1sq m both for their HT and LT models which makes zero sense.  I have yet to check others.  MCS requires installers to conform with any cylinder requirements specified by hp manufacturers.

I'm waiting for the moment when you are going to take the decision to just insulate your home such that it would be futile to want to install any heating system.

 

[JamesPa]

4 hours ago, DanDee said:

I'm waiting for the moment when you are going to take the decision to just insulate your home such that it would be futile to want to install any heating system.

 

Ha Ha

 

Not really doable in a messed about with 1930s solid wall house.  The next occupants may well demolish it though.

[JohnMo]

 

5 hours ago, DanDee said:

waiting for the moment when you are going to take the decision to just insulate your home

Or just move to a house that is or can be insulated and maybe already has a heat pump or where one can be easily installed.

 

Leave your current house for the next owner to leave as is, or bulldozer.

[sharpener]

16 hours ago, JamesPa said:

Now we need the manufacturers of HT heat pumps on board.  Daikin for example specify a min coil area of 1.1sq m both for their HT and LT models which makes zero sense.  I have yet to check others.  MCS requires installers to conform with any cylinder requirements specified by hp manufacturers.

 

FYI I had the following from Vaillant tech support in respect of the Arotherm Plus (R290) HPs:

 

"The rule of thumb for sizing a coil surface area for a heat pump is 'for every 4kw of heat you need 1m2 of surface area'. This would indicate a 12kw unit would need a 3m2 surface area coil within the cylinder."

 

which to my mind demonstrates a woeful lack of understanding of the product that they promote as being capable of 75C flow temp.

 

I am continuing to press them for a better answer.

[JamesPa]

46 minutes ago, sharpener said:

 

FYI I had the following from Vaillant tech support in respect of the Arotherm Plus (R290) HPs:

 

"The rule of thumb for sizing a coil surface area for a heat pump is 'for every 4kw of heat you need 1m2 of surface area'. This would indicate a 12kw unit would need a 3m2 surface area coil within the cylinder."

 

which to my mind demonstrates a woeful lack of understanding of the product that they promote as being capable of 75C flow temp.

 

I am continuing to press them for a better answer.

Interesting.  That's a 'rule of thumb' not a specification.  The MCS requirement is that you must meet manufacturers specifications not their 'rules of thumb'.

 

As you say a woeful misunderstanding of their own product.  

 

I feel a trawl through their installer guide coming on.

Edited August 2, 2023 by JamesPa

[JohnMo]

49 minutes ago, sharpener said:

rule of thumb for sizing a coil surface area for a heat pump is 'for every 4kw of heat you need 1m2 of surface area'.

I believe that would discount most people using their cylinder, I read the specs a while ago and the coil looked quite small for a heat pump cylinder 

[HughF]

14 minutes ago, JohnMo said:

I believe that would discount most people using their cylinder, I read the specs a while ago and the coil looked quite small for a heat pump cylinder 

The 150ltr slimline Vaillant hp cylinder has a 1m2 coil.... I've posted a reheat curve over in the other thread...

Edited August 2, 2023 by HughF

[JamesPa]

4 minutes ago, HughF said:

The 150ltr slimline Vaillant hp cylinder has a 1m2 coil.... I've posted a reheat curve over in the other thread...

Really?  So I can buy this with a 10kW, or even a 7kW, Vaillant heat pump and violate their rule of thumb?

 

Or is it just that they are happy as long as you buy Vaillant?

Edited August 2, 2023 by JamesPa

[JohnMo]

 

4 minutes ago, JamesPa said:

So I can buy this with a 10kW, or even a 7kW, Vaillant heat pump and violate their rule of thumb

Think most the suppliers make it up as they go along. 

[HughF]

15 minutes ago, JamesPa said:

Really?  So I can buy this with a 10kW, or even a 7kW, Vaillant heat pump and violate their rule of thumb?

 

Or is it just that they are happy as long as you buy Vaillant?

Somewhere in the Vaillant documentation there is a selector chart of which cylinder can be used with which HP.

 

I bought it because it was cheap, local, and will fit my cylinder cupboard. Chris at Cool Energy didn't fall off his chair when I told him his 9kW unit would be driving a 1m2 coil...

Edited August 2, 2023 by HughF

[sharpener]

2 hours ago, JamesPa said:

Really?  So I can buy this with a 10kW, or even a 7kW, Vaillant heat pump and violate their rule of thumb?

 

Or is it just that they are happy as long as you buy Vaillant?

 

From https://www.vaillant.co.uk/specifiers/products/cylinders/:

 

 

coil SA is

145l slimline 1.0 m^2

200l  1.4

250l  2.4

300l  2.8

 

So you are correct, they are a long way from meeting their own recommendation of 1.75 m^2 for the 7kW unit, and a factor of >2 out on requiring 3.0 for the 12kW.

 

 

[Beelbeebub]

1 minute ago, sharpener said:

 

From https://www.vaillant.co.uk/specifiers/products/cylinders/:

 

 

coil SA is

145l slimline 1.0 m^2

200l  1.4

250l  2.4

300l  2.8

 

So you are correct, they are a long way from meeting their own recommendation of 1.75 m^2 for the 7kW unit, and a factor of >2 out on requiring 3.0 for the 12kW.

 

 

Wonder if it is to shepherd you towards their products.  If they require a much higher spec for 3rd party stuff than they require for their own it gives them an advantage?

[JohnMo]

22 minutes ago, Beelbeebub said:

Wonder if it is to shepherd you towards their products.  If they require a much higher spec for 3rd party stuff than they require for their own it gives them an advantage?

 

Average punter doesn't buy their products, installers do, they most likely will do a one stop shop anyway, one invoice. Poor punter that gets the final bill will be given some claptrap about being matched units, so really efficient. Hence the high price, and your grant is paying for it anyway.

[HughF]

28 minutes ago, sharpener said:

 

From https://www.vaillant.co.uk/specifiers/products/cylinders/:

 

 

coil SA is

145l slimline 1.0 m^2

200l  1.4

250l  2.4

300l  2.8

 

So you are correct, they are a long way from meeting their own recommendation of 1.75 m^2 for the 7kW unit, and a factor of >2 out on requiring 3.0 for the 12kW.

 

 

Note that the 150ltr is also fine for the 11kW aerotherm (r32)...

 

Either way, nice cylinder, cheap price, fits in my airing cupboard....

Edited August 2, 2023 by HughF

[sharpener]

11 minutes ago, HughF said:

Either way, nice cylinder, cheap price, fits in my airing cupboard....

 

But as you say, with an HP from Cool Energy who are much more relaxed about the whole thing.

[JamesPa]

1 hour ago, Beelbeebub said:

Wonder if it is to shepherd you towards their products.  If they require a much higher spec for 3rd party stuff than they require for their own it gives them an advantage?

Do Vaillant actually specify any requirements for a third party dhw cylinder.  I couldn't find anything in their installers guide.  A rule of thumb isn't a specification and can be ignored.

[sharpener]

 

5 hours ago, JamesPa said:

Do Vaillant actually specify any requirements for a third party dhw cylinder.  I couldn't find anything in their installers guide. 

 

Can you give a link for that? I have got the installation instructions <arotherm-plus-230v-double-2626669.pdf> for the twin-fan units but there is nothing at all about constraints on DHW cylinders, only that they need min 150l of engaged volume (45l with the auxiliary heater fitted) - this would seem to be about defrosting though.

 

5 hours ago, JamesPa said:

A rule of thumb isn't a specification and can be ignored.

 

Not if you want the 7 yr extended warranty which is only available via approved installers, and can't find an installer who will fit the HP to your existing tank without running it past Vaillant for pre-approval which to date has not been forthcoming.

 

I am persisting with this bc their units are R290 and have an unusually narrow footprint (only 605mm including air space behind) but there will be rival products out in 2024. And it is already getting late for this season as the P/P is not due until 12 September.

[HughF]

19 hours ago, JamesPa said:

Do Vaillant actually specify any requirements for a third party dhw cylinder.  I couldn't find anything in their installers guide.  A rule of thumb isn't a specification and can be ignored.

I doubt anyone installing Vaillant will be using anything other than a Vaillant cylinder, so I expect there is nothing in the specs on what 3rd party cylinder requirements are.

[JohnMo]

I suppose if you're a manufacturer, why would you bring up the subject that there could be other options, that sway you to do anything other, than their cylinder.

 

If you mess up by choosing the wrong cylinder, that's your problem not theirs.

 

Looked in my Maxa manual, it doesn't state anything other than if the coil size is to small it will learn this and shut down early, so you don't keep hitting the max temperature stop and go into a repeat short cycling.

[HughF]

12 minutes ago, JohnMo said:

I suppose if you're a manufacturer, why would you bring up the subject that there could be other options, that sway you to do anything other, than their cylinder.

 

If you mess up by choosing the wrong cylinder, that's your problem not theirs.

 

Looked in my Maxa manual, it doesn't state anything other than if the coil size is to small it will learn this and shut down early, so you don't keep hitting the max temperature stop and go into a repeat short cycling.

Yep, fair point...

[HughF]

https://www.ebay.co.uk/itm/185631610657?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=yawjptzcrle&sssrc=2047675&ssuid=&widget_ver=artemis&media=COPY

 

Interesting..... I wonder who makes this...

[DanDee]

9 minutes ago, HughF said:

https://www.ebay.co.uk/itm/185631610657?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=yawjptzcrle&sssrc=2047675&ssuid=&widget_ver=artemis&media=COPY

 

Interesting..... I wonder who makes this...

in the meantime

https://www.shopclima.it/en/mitsubishi-electric-pxz-4f75vg-2x-msz-ap25vgk-msz-ap35vgk-erst20d-vm2d-ecodan-multi-3-1-pxz-r32-system-with-msz-ap-wall-units-and-200-l-hydrotank-7-5-kw.html

[JamesPa]

32 minutes ago, JohnMo said:

I suppose if you're a manufacturer, why would you bring up the subject that there could be other options, that sway you to do anything other, than their cylinder.

 

If you mess up by choosing the wrong cylinder, that's your problem not theirs.

 

Looked in my Maxa manual, it doesn't state anything other than if the coil size is to small it will learn this and shut down early, so you don't keep hitting the max temperature stop and go into a repeat short cycling.

Daikin, for some reason do.  But I agree with your logic and it's better if manufacturers don't because then there is no poorly thought through backside covering spec for MCS to insist you follow.

Edited August 3, 2023 by JamesPa

[DanDee]

19 hours ago, JamesPa said:

Do Vaillant actually specify any requirements for a third party dhw cylinder.  I couldn't find anything in their installers guide.  A rule of thumb isn't a specification and can be ignored.

[JamesPa]

3 minutes ago, DanDee said:

Absolutely perfect, it says nothing so imposes no silly constraints.

 

Edited August 3, 2023 by JamesPa