Posted by: @alex6547

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Has anyone tried or seen the hot water cylinder for a heat pump outside the house in an insulated shed or something similar? I live in a small house and sacrificing one of the wardrobes to have a cylinder in place has been bothering me for a while. I thought about putting the cylinder outside, building an insulated structure around it. At first, I don’t see any issues with that, it possibly allows me to have the cylinder and the heat pump a bit further away from the house as well as I'm learning about underground insulated pipes and the costs associated.

What are your thoughts on that? I can see on the technical specs of Vaillant Aeroterm plus as 20 metres as the maximum distance, I guess that is between the monobloc and the water cylinder? I guess I can get them close to each other, but distant from my house.

I've no idea how much loss of efficiency I'll have by using underground insulated pipes, but from initial research it seems that it may be negligible as underground the temperature is always 13c all year, including when it is -5c outside, and the pipe insulation looks to be pretty good.

Have you considered putting the hot water cylinder in the loft if you have one?

there is discussion on this thread https://renewableheatinghub.co.uk/forums/safety-regulations-tools-diy-installations/some-big-changes-are-coming-to-heat-pump-installation-training/paged/2 about a "combi" style of heat pump being under development. which addresses this exact issue for houses with little space for a cylinder. might be worth giving heacol a ping.

@iancalderbank

You could also consider a SunAmp if you have limited space.

@derek-m yes good point with sunamp. although not for me, for the OP 😉

Posted by: @alex6547

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Has anyone tried or seen the hot water cylinder for a heat pump outside the house in an insulated shed or something similar?

Yes [for hot water / not sure if it was hot water & heat pump], the build and installation video is on YouTube [somewhere].  Tried to find it but can't, if I find it will post back here.  It was a mixergy cylinder.  Installed into water tight insulated shed on the side of the house.

@derek-m my loft is going to be converted later, so the cylinder needs to go somewhere else first, and even when we convert the loft I'm not convinced it is worth putting the cylinder over there as the house is quite small.

Posted by: @iancalderbank

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there is discussion on this thread https://renewableheatinghub.co.uk/forums/safety-regulations-tools-diy-installations/some-big-changes-are-coming-to-heat-pump-installation-training/paged/2 about a "combi" style of heat pump being under development. which addresses this exact issue for houses with little space for a cylinder. might be worth giving heacol a ping.

I read the whole thread, but I didn't see anything about what you mentioned. Am I missing something? I'm send him a PM.

Ah dam, I need to post 10 times before PM someone...

Posted by: @derek-m

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@iancalderbank

You could also consider a SunAmp if you have limited space.

That is quite interesting, I didn't know it could be used as a replacement for a cylinder. I could not find much on youtube, are there people here in this forum using it?

Posted by: @william1066

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Posted by: @alex6547

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Has anyone tried or seen the hot water cylinder for a heat pump outside the house in an insulated shed or something similar?

Yes [for hot water / not sure if it was hot water & heat pump], the build and installation video is on YouTube [somewhere].  Tried to find it but can't, if I find it will post back here.  It was a mixergy cylinder.  Installed into water tight insulated shed on the side of the house.

Thanks, I hear about this brand before, I'll try to get some information about it for outdoor use

@alex6547 sunamp is very much designed as a cylinder replacement. Its a salt solids based heat battery, it doesn't have water in. Those solids have a significantly higher energy density than water .  Hence much smaller for same amount of "equivalent hot water storage". There are installation photos , if you get googling, showing a full sized cylinder replaced by a device the size of a thin fridge. But there are trade offs.  price being the most obvious! There is quite a bit discussion of them, and those trade-offs, on buildhub.org.uk.

mixergy is still a cylinder with water in, albeit with an optimised design, so subject to the same laws of physics as a "standard" cylinder with regard to  size and heat loss. there isn't any fundamental reason why a cylinder outside won't work, you will just need to weather proof it, and absolutely insulate the **** out of everything otherwise its heat loss is going outside , you need to be really careful about any freeze vulnerability points.

the comment by heacol that I was referring to was this one below - it sounds like this is under development, not a thing you can actually buy. but you can ask him.

....3/4 of the way through developing exactly that. It has already been independently tested by Ulster University and as taken 7 yeas to get here. We are not too far room the launch. There will also be a heat pump combi version, which is a direct like for like replacement for a combi boiler, not requiring a hot water cylinder.