@adamk 

Yes, it's a good way and an alternative to (or supplementary to) the coil.  Some say it's better and, other than the need for an extra pump, it's a reasonable argument.  It will need an auxillary pump to circulate the dhw through the phe.

Need help with a diagram of what’s need for a base for a 7kw Vaillant. Also what the optimal gap to leave between the wall of the house and corner of the house? Nothing in front or either side of the HP apart from a soil vent pipe that runs up the back of the property.

also where does the condensate go? Don’t have a gully at the back of the house.

having to ask all this as installer is 70 miles away and can only come and fit for 3 days.

My installers also asked me to have the base ready for them, and after giving it some thought, I just popped down to the builders’ merchants and picked up four 50cm x 50cm concrete slabs. I levelled the ground, mixed up a bit of cement, and created a simple base using the angle of repose as my guide. Heat pumps are heavy, so everything settled in nicely and it’s been rock solid for six years.

For condensate drainage, will the area where you’re installing it be gravelled? That can help a lot with dispersing the water.

Posted by: @adamk

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Need help with a diagram of what’s need for a base for a 7kw Vaillant. Also what the optimal gap to leave between the wall of the house and corner of the house? Nothing in front or either side of the HP apart from a soil vent pipe that runs up the back of the property.

also where does the condensate go? Don’t have a gully at the back of the house.

having to ask all this as installer is 70 miles away and can only come and fit for 3 days.

Agree with @mars.  There is also a diagram in the Vaillant installation manual.  Careful with condensate - it freezes so you really don't want it running over somewhere you are likely to walk, straight into a gravel bed or a gully is the best.  

was due to have the HP installed next Monday. now dont have an installer and just got two 28mm pipes sticking out the wall i had my plumber put in ready. BUS app has had to be cancelled, deposits returned, basically a cluster F from start to finish. 5 months nearly 6 and im back to square one. how the hell does anyone get a competent and focused installer at the moment? part of me wishes id stuck with Octopus and put up with there odd ways just to get the job done then i could tweak it to make it more efficient, but that ship sailed when i cancelled the process to go with and installer that should have been a better experience and more efficient. they weren't local which i think was the main issue and caused most of the problems, like trying to do a heat loss survey over teams etc.

why do people say go with a local firm, if i check Vaillant or Heat Geek the nearest installers are 20+ miles away.

Posted by: @adamk

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why do people say go with a local firm, if i check Vaillant or Heat Geek the nearest installers are 20+ miles away.

The "local installer" advice doesn't really work for heat pumps because frankly, there just aren't enough good ones around yet. The decent installers end up covering wide areas because demand outstrips supply - that's why you're seeing the nearest recommended ones 20+ miles away.

I've said this before in DMs and emails, but it's absolutely worth waiting for a proper installation rather than rushing into a bad one with whoever happens to be closest. I know how frustrating this is, especially after being messed around already. You're in one of those areas that's poorly served for quality heat pump installers right now - and that's the single biggest barrier to heat pump adoption in the UK.

This won't change until we get more installers properly trained up. For now, the reality is you might need to accept an installer traveling to you if you want it done right. I’m still trying to find you an alternative that’s recommended. 

@editor ive got GT Heatspec (Vaillant Master Tech) and TF Heating (Vaillant renewable partner) having a look. Earthnrg were the only other one listed and they never got back to me after a site visit.

@adamk It can be vey frustrating; I first contacted Octopus Energy (who helped me to establish just what might and might not be possible or advisable), they were unable to carry out the installation for our peculiar requirements at that time in 2022 [though they probably would be able to do so now]. I spent a whole year researching the project and subsequent to the 8 legged survey and  experience, I contacted 20 (yes TWENTY!) installers; many did not reply, others said they didn’t cover out area … and we were left with 5 possibles, one of these quoted then said ‘Oh we don’t cover your area - good bye’, one did a 5 minute walk around the house and was going to quote there and then - but I showed him the door. We decided from the other three candidates by merit, price and our gut feelings - as it turned out, we did well! Regards, Toodles.

this is why the govs plan to fit 600k of these things is for the birds. ive spoken to another youtuber who thinks the BUS grant should be scrapped and let the market forces decide price, as he said some installers are using the BUS grant increase to increase profits. i can believe this to some extent as i noticed this happening when solar water heating was being funded many years ago. but i think looking at some quotes i have there is still quite a lot of expensive kit on them which if there was no BUS grant they would in no way be able to do the job for the prices ive had after the BUS.

Posted by: @adamk

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this is why the govs plan to fit 600k of these things is for the birds. i

Which, if you are right (which you may be), is unfortunate to say the least, because climate change and the catastrophic effects it is certain to have wont go away just because we don't know how (or, more realistically, don't have the political will) to deal with it, and there appears to be no realistic alternative way to decarbonise domestic heating.

That said, getting installers up to speed is something that develops over time.  Obviously we should have started earlier and been more determined, but we didn't, instead we faffed around for decades (and to a significant extent, are still faffing around).  Getting there late is still likely better than not getting there at all.

warning - rant follows!

TBH I am not at all convinced that there needs to be a problem. 

Installing a heat pump is barely more complicated than installing a gas boiler and any plumber should be able to do it.  The industry has made it complicated by introducing buffer tanks/low loss headers/plate heat exchangers and a complicated and not particularly accurate way to calculate heat loss.  Furthermore it excluded local plumbers from the market by making MCS a condition of permitted development. 

Most normal size retrofits will be in the region 3-8kW, the whole of which is covered perfectly well by the 8kW r290 Ecodan, which has both a 6 and a 2kW compressor.  A simple check of gas consumption will suffice to verify that any given house is in this range, but realistically you arent going lower than say 4kW anyway because you need to heat DHW, so 'verification' amounts to checking that the loss is not more than 8kW.  Most will be.  Rad sizes can then be proportionated, erring on oversizing unless physically it wont fit (you can turn down but not up!).   DHW could be solved by retrofitting a circulator pump and PHE to the existing cylinder and reusing existing pipework, or where there is a combi using a PHE plus 3kW willis heater for real time 9-11kW, which is the same or better delivery rate as an electric shower.  Provided you are prepared to think out of the box you could do away with the need to plumb the vent for a UVC (which can be a pain) by designing the PHE plus willis heater combo with inbuilt safety features guaranteeing that the tank was never fed with water at >say 80C thus saving another tiresome and disruptive job.

Obviously some of this is only just becoming clear and we need a couple more manufacturers to offer 'wide modulation' units, but with a major reset in thought processes and some out of box thinking we could do much, much better than we are currently doing with the people we currently have.  Unfortunately the sponsors of MCS are probably content with a low volume high price market so will likely continue to regulate in a way that makes this difficult to impossible.  But if we put some thought into it I am pretty certain it could be solved, probably better by those on this forum than by the industry.  Hopefully Octopus and BG, who I understand are more focussed on volume, will sort this out, I can see MCS applying itself to the problem of enabling any local plumber to do the job, they have a closed shop to protect.

The real target is 1.5M per year BTW, which is the number of gas boilers fitted.  The only way that is going to be achieved is if the existing workforce, ie local plumbers, do it.  So we need to accept this and make it happen!

end of rant!