heat pump design

[HughF]

The engineers who are specifying buffers and new cylinders are just copying install schematics out of the big Vaillant book. They’re not doing anything particularly wrong, its just the options in the book aren’t very good for the UK where we have to chase the SCOP to get a system that’s on par with gas.

[JamesPa]

58 minutes ago, HughF said:

The engineers who are specifying buffers and new cylinders are just copying install schematics out of the big Vaillant book. They’re not doing anything particularly wrong, its just the options in the book aren’t very good for the UK where we have to chase the SCOP to get a system that’s on par with gas.

Yes they are doing something wrong, buffers are not needed in almost all cases and in the way they are generally fitted both cripple COP and make fault diagnosis impossible.  Electricity prices aren't that different in the UK to those in several other European countries and efficiency is important to everyone so far as I know, irrespective of nationality.

 

There are Vaillant schematics with buffers and schematics without buffers.  There are schematics showing things you may not fit.  This is intentional as every house is different. 

 

Those doing the design need to do the job properly or get out of the business if they are not capable, cant be bothered or haven't bothered to understand how a heating system works, preferably before they destroy the whole industry.  

 

 

PS they aren't engineers, they are fitters.  Engineers are professionals who can think about what they are doing and apply intelligence, logic and knowledge to the problem at hand.  Fitters do painting by numbers.  Absolutely nothing wrong with fitters, we need them and they have valuable practical skills, but they shouldn't be allowed to do design until they have demonstrated that they have the required capabilities.   Brunel, Stephenson, Telford and the like would be turning in their graves!

Edited September 23 by JamesPa

[jit]

On 19/09/2025 at 12:38, JamesPa said:

 

Just be aware 7hrs cheap rate on the immersion may not be enough so some may be at full price and full recovery is going to take a fair time.  It depends on how demanding your users are!  As you are an electrical engineer you can do the math without our help!

i got 10kw solar panel and 16kw battery pack installed. in summer is no issue at all at it produce 60-90kw and in winter i am starting to see drop but even bad days producing between 15kw - 30kw. i can also charge from grid at 7p with my 16kw battery. there lots of option when it comes to cheaper fuel . and the heat lost calculation might be 7kw or even less if surveyor not input right U - value. this is why i am prepare to take risk. i just needed profession opinion to confirm if i am on right track or if i should do somethign different 

On 19/09/2025 at 12:38, JamesPa said:

 

Just make sure you are not lumbered with buffer or unnecessary external controls.  Vaillant heat pumps come with all the controls you need other than manual (set and forget) balancing valves.  If your chosen engineer insists, choose another!

i am not installing buffer. totaly against. if its needed . i can alway install it after. my brother in law is plumber. so if any work need to be carried out after then can be done .

[jit]

1 hour ago, HughF said:

The engineers who are specifying buffers and new cylinders are just copying install schematics out of the big Vaillant book. They’re not doing anything particularly wrong, its just the options in the book aren’t very good for the UK where we have to chase the SCOP to get a system that’s on par with gas.

i agree. the system on Vaillant schematic book are design in consideration of all the property in uk . while most of property don't need it if your good installer. the way i see buffer is, it is made for diy installer which allow error and high tolerance in incorrect sizing  but reduces efficiency of heat pump

[JamesPa]

18 minutes ago, jit said:

i got 10kw solar panel and 16kw battery pack installed. in summer is no issue at all at it produce 60-90kw and in winter i am starting to see drop but even bad days producing between 15kw - 30kw. i can also charge from grid at 7p with my 16kw battery. there lots of option when it comes to cheaper fuel . and the heat lost calculation might be 7kw or even less if surveyor not input right U - value. this is why i am prepare to take risk. i just needed profession opinion to confirm if i am on right track or if i should do somethign different 

i am not installing buffer. totaly against. if its needed . i can alway install it after. my brother in law is plumber. so if any work need to be carried out after then can be done .

Sounds like you have it all sorted!  Excellent and good luck.  If my experience is anything to go by you wont regret it.

Edited September 23 by JamesPa

[JamesPa]

12 minutes ago, jit said:

the way i see buffer is, it is made for diy installer which allow error and high tolerance in incorrect sizing  but reduces efficiency of heat pump

nah, they are made for sloppy installers who see buffers as a way to avoid taking any responsibility for the downstream equipment, cant or wont do even approximate head calculations, and who want to avoid call outs due to low flow and several other problems which should be fixed, but with which your system will limp on if a buffer is fitted.   There are still, sadly, loads of 'professional' installers who insist on fitting buffers on all occasions, and who should be struck off on account of the (possibly irreparable) damage they are doing to the industry with their poorly performing systems (not just due to buffers, admittedly).

 

There are of course some rare cases where a buffer is a good thing and the only viable solution, but if you start with the premise (a) that it isnt needed until proven otherwise and (b) alternatives that don't involve system separation have been discarded, you wont go wrong.

 

If there was ever any doubt about this - over on RHH the editor has run 2 podcasts on separate occasions where he has invited installers who advocate against buffers and installers who advocate for buffers.  Only those in the first category were prepared to take part on either occasion.  That says everything you need to know.

Edited September 23 by JamesPa

[HughF]

1 hour ago, JamesPa said:

PS they aren't engineers, they are fitters.  Engineers are professionals who can think about what they are doing and apply intelligence, logic and knowledge to the problem at hand.  Fitters do painting by numbers.  Absolutely nothing wrong with fitters, we need them and they have valuable practical skills, but they shouldn't be allowed to do design until they have demonstrated that they have the required capabilities.   Brunel, Stephenson, Telford and the like would be turning in their graves!

I wasn't going to go down that rabbit hole, but I agree with you. Me, engineer - I design PCBs, write firmware, design enclosures, design wiring harnesses. Others in my company, fitters - they assemble the product.

 

I only used the term as it's the preferred vernacular in industry (for better or worse).

 

Interesting, the LG book shows a buffer and then an LLH after the buffer 😁

[saveasteading]

18 minutes ago, HughF said:

it's the preferred vernacular

Preferred  by non-technical people and some fitters to escalate the credibility of the fitter who is being sent.

Technician is a good term. I'd rather have my meter changed, as last week, by a trained technician than by a Chartered Electrical Engineer.

 

My personal annoyance is a man with a shovel  having "Civil Engineer" on his van. However good he is at it.

Better him on the shovel than me, as long as he doesn't tell me that a building is designed badly.... they often do. The less knowledge, the more certainty.

 

It's not a  protected term like "Architect". But even that seems to be under threat by new terms like 'Technical Architect' with capitals: meaning I think, draughtsman, or architectural technician. Again nothing wrong with the role, but perhaps misleading the public.

Architect seems to be appropriated by the software industry too.

 

So I do make a point of a capital E for professionals, and never use the word  where it should be technician. Snobby? No. Accurate and informative.

 

[HughF]

3 minutes ago, saveasteading said:

Preferred  by non-technical people and some fitters to escalate the credibility of the fitter who is being sent.

Technician is a good term. I'd rather have my meter changed, as last week, by a trained technician than by a Chartered Electrical Engineer.

 

My personal annoyance is a man with a shovel  having "Civil Engineer" on his van. However good he is at it.

Better him on the shovel than me, as long as he doesn't tell me that a building is designed badly.... they often do. The less knowledge, the more certainty.

 

It's not a  protected term like "Architect". But even that seems to be under threat by new terms like 'Technical Architect' with capitals: meaning I think, draughtsman, or architectural technician. Again nothing wrong with the role, but perhaps misleading the public.

Architect seems to be appropriated by the software industry too.

 

So I do make a point of a capital E for professionals, and never use the word  where it should be technician. Snobby? No. Accurate and informative.

 

'Surface coating engineer' - glorified painter and decorator

[JamesPa]

47 minutes ago, saveasteading said:

Preferred  by non-technical people and some fitters to escalate the credibility of the fitter who is being sent.

Technician is a good term. I'd rather have my meter changed, as last week, by a trained technician than by a Chartered Electrical Engineer.

... which is part of the problem. 

 

With the possible exception of surgeons we have a thing in this country that 'manual' skills are somehow less valuable than 'intellectual' skills.  This is of course nonsense, we need both, they are complementary, and they aren't interchangeable (although some people have the fortune to be good at both). 

 

We need to change our mindset and appreciate both equally, and differentiate where necessary.  Until we do people with first class skills in soldering, excellent spatial awareness and attention to detail (or not in some cases these days) and body flexibility will continue to be allowed to 'design' heating systems.  Madness, as we can see from the results!

Edited September 23 by JamesPa