Posted by: @toodles

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@jamespa When I contracted a company to install my solar energy system and battery, I was allocated a ‘surveyor’ to ascertain the best arrangement of panels, their positioning, the wiring runs, position of battery and means of connection to my CU and the earthing system etc. By the time it came to the installation, the surveyor had passed on the project to a ‘project manager’. It turned out the PM was a trainee, wet behind the ears and possibly straight from university. The PM’s experience was zero, her competence was through the floor and the various contractors would roll their eyes upon the mention of her name. The result was an installation that took three times longer than estimated with much equipment delivered having to be returned as unsuited to the task, roofers sitting around for three days in high temperatures doing very little waiting for supplies and work having to be re-done later. @asoksevil , if you have several or more contractors involved, please make sure you have a competent Project Manager in overall charge! Regards, Toodles.

Situation normal for the construction industry then!

Posted by: @jamespa

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Thanks for the further details.

I understand you are prepared to pay money for a quality job, my concern is that you are paying lots of money for a poor design.

Really you need to get some quotes from people who both know what they are doing and aren't intending on ripping you off. The quotes you have seem to indicate that neither apply in this case.  Vailant is a perfectly good choice of heat pump, and natively supports above dew point cooking (you need the cooling dongle). The choice of heat pump is not the problem!

I am not convinced it makes sense to try to redesign this on this forum at this stage, because the problem appears to be the contractors so it's unlikely they will change, however, as a starting point,

replace the 4 port buffer with a 2 port volumiser in either flow or return but not both.  This will have the same effect on cycling without the downsides.  Buffer tanks do not affect hot water so someone is misinforming you.

Eliminate all external controls and zones

Work out if this is light cooling IE above dewpoint or sub-dewpoint cooling in the latter case what is the plan to condensation proof the pipework etc?

Review whether you really need 2 sets of emitters and why.  Consider a2a for cooling or even for cooling plus heating given floor area plus standard of insulation.

Sunamp is a fair choice if no space.  However tank in loft arguably better if it will fit.  Tank could be split into two if a single 300l won't go through loft hatch.

 

My strong recommendation is get some more quotes. You could ask vaillant for local accreditted installers.  Whatever you don't proceed as is and if you are really contemplating sub dewpoint cooling then the pipework will need to be sealed while the flooring is up!  

This is exactly my concern, I am paying a lot of money and if you think into the overall renovation, the professional fees applied here is already high. I actually don't know that many installers, I've tried your energy your way which I believe has been featured here and I was referred from them as they couldn't do it in London. I was happy for Vailliant, it's just that the other options I have combined the A2A and A2W to have all of these into one. I am not sure the Vailliant is A2A.

Our cooling designer has been engaged not just to design the cooling part but to be overall responsible that everything will work as designed. 

thank you!

Posted by: @jamespa

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All (or most) of the above points are entitely valid, but above all what this project needs is a coherent design by someone who actually knows what they are doing.  If the actual work is split that's fine, but the design shouldn't be.  One person needs to take responsibility for heating, cooling and control design.

 

@asoksevil I think that first and foremost you need to decide whether you are going to seek someone competent to do this, or try to do it yourself by arbitrating between the people you have and the various bits of advice you will get here.  In the latter case you are effectively taking responsibility for the design because the installers will inevitably say that they advised something else, but you declined to follow them.  There is absolutely nothing wrong with that approach, it's your house and you have the vested interest, you just need to be comfortable with what you are doing.

Unfortunately I don't have the time nor the expertise to do this so I am happy to pay a competent individual to do the job but it is hard to because I cannot audit it myself when I am not competent enough in the area, no real benchmark, the myriad of options and my gut feel is that everyone wants to rip me off, get paid and not be accountable for whether the solution provided would ultimately work. Are there any people you could recommend within London? Like I said I have already engaged a passive house designer, got several accreditations and so is my architect and yet these is apparently their recommendation.

Posted by: @asoksevil

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Unfortunately I don't have the time nor the expertise to do this so I am happy to pay a competent individual to do the job...

 Are there any people you could recommend within London

Fully understood and entirely reasonable!  On the home page of this site you will find a 'find an installer' form with hand picked recommendations from the site editor.  Alternatively call vaillant (or another chosen heat pump manufacturer) and they will give you typically 3 referrals (they don't do recommendations).  Or you could try the heat geek network. 

You might have to look around quite a bit because not many are switched onto both heating and cooling other than the commercial Aircon (aka air to air heat pump) guys who tend not to bother with domestic jobs.  If you have a written spec for the job it's easy to eliminate those who just do not do this sort of job.

Posted by: @asoksevil

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my gut feel is that everyone wants to rip me off, get paid and not be accountable for whether the solution provided would ultimately work. 

It's the construction industry, so whilst not everyone wants to rip you off without taking accountability, it's certainly the case that a proportion do, as in every part of the construction industry (or at least every part I have ever encountered).  Also don't assume competence, many, probably most, in the construction industry are very competent, but a fair few are just chancers.

Fwiw I once had to deal (in a work scenario) with an 'M and E' contractor recommended by a very good architect.  The m and e contractor  was engaged to design a heating system for a domestic size meeting space.  They hadn't got a scooby, and I was left with no choice but to dismiss them.  Fortunately the main contractor for the build did know what they were doing and did the design instead 

That's why it's best to draw up a clear written spec and get at least 3 quotes, I would say preferably more than 3 given the task.  Getting multiple quotes isn't just about price, it's about understanding the options as different people will quote different systems.  You may need two rounds because the first might refine the requirement!  Also ensure one contractor has overall accountability.  It's quite normal for ufh to be installed by a separate contractor (but you need to ensure it isn't saddled with unnecessary controls and mixing) but rare for radiators to be separated in this way. Either way it's important someone has overall responsibility even if it's just reviewing and approving the spec of (eg) the ufh.

If you want some commentary on a draft spec, feel free to post it.

Hope that helps although I realise it's not the simple solution you were probably looking for, maybe one of the installers on here will offer to do the job or someone will come up with a simpler approach to getting quotes.

Another alternative is to proceed anyway with just a few amendments (eg volumiser not buffer, checking the bit about vapour sealing, perhaps a couple more) and then set the controls in a way that disables the unnecessary stuff.  So long as they don't do anything that can't be worked around without replumbing/rewiring that is probably the quickest, but will require input from you which you say you don't have the time to do.