@samiebon1 Sounds like some rowlocks are being bandied about to me…. Toodles.

Posted by: @jamespa

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Assuming you are in England then the 1m from boundary rule applies.  I think it does elsewhere but would have to check to be certain. 

...and any attempt to suggest otherwise is most certainly a red flag until proven to be a valid piece of advice. As @editor said as well, what the potential installer has told you is rather screaming of "proceed with caution" at the very least.

@editor @jamespa Thanks both. The installer is part of a company (not one man band) and sounds experienced but the things they're saying are a bit... odd.

They haven't said volumiser, only buffer. I think i'll push back a bit when they say Buffer (i'm an engineer so have some form of competence!). I've got a couple of companies coming to survey so will challenge and update you all!

Edit: Based in Manchester, England.

An update after I had some more interaction with those potential installers:
One had said the buffer was needed not technically but to cover manufacture warranty as thats how they specify the design (which made sense but would value other's experience/input).
The other installer, when I challenegd on buffer and said the size of my heating system (~200L) he fully accepted that a buffer wasn't needed.
Both however are still a bit lessay fair about the 1m distance and have only said it needs to have the fan pointing away. Makes technical sense and might be something along the lines of what I hear the MCS are looking to remove from requirements... but current guidance/requirments still says 1m.

Posted by: @samiebon1

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Both however are still a bit lessay fair about the 1m distance and have only said it needs to have the fan pointing away.

. Makes technical sense and might be something along the lines of what I hear the MCS are looking to remove from requirements... but current guidance/requirments still says 1m.

This a matter of law not an MCS decision or even guidance.  End of unless you want to apply for planning permission.

https://www.legislation.gov.uk/uksi/2015/596/schedule/2/part/14/crossheading/class-g-installation-or-alteration-etc-of-air-source-heat-pumps-on-domestic-premises

Posted by: @samiebon1

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One had said the buffer was needed not technically but to cover manufacture warranty as thats how they specify the design (which made sense but would value other's experience/input).

You mention it's a Vaillant.  As it happens I was looking at their their standard plumbing diagrams yesterday and certainly the one I looked at shows a 2 port volumiser (but not a buffer tank).  What I'm not sure is whether the text clarified the conditions under which it's necessary (basically if you haven't got sufficient system volume). Unfortunately installers appear to have a habit of assuming that if it's in the diagram it's necessary, which is not always true. 

Vaillant tech support are very helpful so you / your installer could ask the question. 

Don't accept a 3 or 4 port buffer, there are definitely diagrams in the Vaillant approved set that have only a volumiser so you are being given bs if they say a 3 or 4 port is necessary to cover manufacturers warranty.  If they insist look elsewhere.

@samiebon1, I can confirm that not installing a buffer won’t void the warranty. This comes directly from Vaillant, who do not require a buffer or volumiser but simply recommend meeting minimum system volume requirements.

I have posted these on the forums before, but have been asked by someone on YouTube how a volumiser differs from a buffer tank visually so reposting here as part of the definitive buffer tank thread.

I wonder if CIBSE have an opinion on or a definition on when to use a buffer, low loss header or volumiser 
 

Just thinking out load as in the Uk standards of excellence, approved codes of practice abd other forms of engineering standard often are derived from organisations such as CIBSE, BESA and so on  

@editor has anyone ever posted on the forum, I had a system installed, they did not fit a buffer but it turns out it needed one so the installer returned and fitted it?
 

Posted by: @ashp-bobba

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@editor has anyone ever posted on the forum, I had a system installed, they did not fit a buffer but it turns out it needed one so the installer returned and fitted it?

No, there has never been a case along these lines. There are, however, quite a few where the opposite has occurred. Buffer fitted with poor system efficiency; the buffer was then removed and the systems have run much better.

@ashp-bobba, after years of conversations with numerous heat pump engineers and industry experts, it’s clear that there’s a significant gap in meaningful, authoritative guidance on best installation practices. Unfortunately, no governing body currently provides comprehensive standards that ensure optimal system performance. This may change in 2025 with the announcement of Flexi-Orb’s scheme, which looks very interesting (and promising).

The real advancements in installation practices have come from experienced engineers like @damon, @heacol, @patrickvito, @ken-bone, etc. who’ve consistently demonstrated that open-loop systems outperform buffered systems in both efficiency and reliability. Their work has been instrumental in driving improvements, but it also highlights the need for broader industry standards to raise the bar for everyone.