Using the Hot Water Tank to Cool the air

[Lexifir]

Hi

 

I'm in the early stages of research and planning a house build. My wife and I both want a Passive or near Passive house, but I'm looking at the heating and cooling issues.

 

 

Heating doesn't seem to be an issue, the house will be near airtight and have a lot of good insulation all over. I also have a fair amount of electronics (servers) that generate plenty of heat. During the winter months, I'm happy that the additional house heating will be on at a very minimal level, if at all...

 

Summer might cause me some issues at the hottest times. I know MVHR can have a summer bypass option, but I don't think that will be enough. I don't want a house that for the odd week in summer (UK) it will be too hot inside. If I was to install AC into some of the bedrooms and other important areas, is it possible to rig the AC so that it either directly or via the heat pump dumps the heat into the hot tank?

 

Also, if anyone has suggested brands, I'm welcome to suggestions as it opens up more research for me.

 

Thanks all!

[JohnMo]

If you want Aircon anyway, use the same unit for heating also - everywhere. For DHW either direct immersion heating, during off peak or get one that heats via its own heat pump. Couple of holes in the wall for air in out.

 

Or just get an ASHP, fan coils in the bedrooms and living space, they will do heating and cooling. Unvented cylinder. Simple.

[ProDave]

The issue being mentioned here, is ASHP's are really simple things, they move heat from A to B.  So in winter when heating the house they cool the air outside.  In summer when cooling the house they heat the air outside.  That is a waste.  The issue is why does nobody seem to make a heat pump where there is an option when cooling, to put the "waste" heat into a hot water tank?

[JohnMo]

9 minutes ago, ProDave said:

The issue is why does nobody seem to make a heat pump where there is an option when cooling, to put the "waste" heat into a hot water tank?

There is an Italian heat pump, that when in cooling mode sends the refrigerant into a cylinder coil for heating DHW. But I cannot remember the company name.  Did try to buy, but UK seller is plain rubbish, never returned calls etc.

[saveasteading]

1 hour ago, ProDave said:

why does nobody seem to make a heat pump where there is an option when cooling, to put the "waste" heat into a hot water tank?

I have asked specialists. It's the size of that tank, and getting it above lukewarm.

 

For one client there was a freezer store and an office. Obviously it would be appropriate to heat the office from the waste heat.

The client engaged  'specialists' direct and they said it was impossible. The office is heated by an oil boiler and rads, while the chillers chuck heat out to the yard

 

Later I met a sustainable energy boffin and asked. He explained that there is some technical reason* that you can only capture about 10% of the heat, and then concentrating it with another heat pump is expensive.

 

* I think it is having a plenum or heat recovery  ducting system that is big enough, then the power in concentrating it.

 

But Mitsubishi and Daikin now have internal modules that will balance out the whims in an office space (one cooling while another heats) . so the liquid all goes to  a central point and averages out and avoiding chucking it away.

 

I read yesterday about the prospects of storing heat in foundations. Carbon black mixed in the concrete seemed to be the thing.

Resin phase change was going to be around by now, but it seems to have gone quiet.

[JohnMo]

59 minutes ago, JohnMo said:

There is an Italian heat pump, that when in cooling mode sends the refrigerant into a cylinder coil for heating DHW. But I cannot remember the company name.  Did try to buy, but UK seller is plain rubbish, never returned calls etc.

Argo, with EMIX cylinder. Does what you want out the box.

https://argoclima.com/en/prodotti/im/

 

There are others, you are looking for the words "de-superheater"

[SteamyTea]

17 hours ago, JohnMo said:

There are others, you are looking for the words "de-superheater"

Can't you get an Ecocent type water heater that draws warm air from the house?

I think it usually expels cooled air to the atmosphere, but a bit of ducting would sort that.

17 hours ago, saveasteading said:

I read yesterday about the prospects of storing heat in foundations. Carbon black mixed in the concrete seemed to be the thing.

Resin phase change was going to be around by now, but it seems to have gone quiet.

There are a lot of ideals that are chasing a small pot of development money.  A friend of mine left a well paid job because his main task was having to shift though bonkers ideas that would never work.

 

Here is a similar conversation.

 

Edited December 30, 2023 by SteamyTea

[Garald]

Having a DHW system that draws heat from air inside the house is actually common: in French, it's called a "chauffe-eau thermodynamique". Two people (one of them in this forum) recommended Atlantic Calypso. Of course these are "heat the water you need and cool the room in the process" not "cool the room as much as you want and heat water in the process."

 

Oddly enough they are not marketed as (it would seem to me) they ought to be: a system to use during the summer months - or (do you know someone who does this well?) something that can be used as part of a poor-man's MVHR system. Instead, it would seem that installers rely on a total lack of physical intuition on the part of customers. (Why on earth do you want to draw heat from the inside of a place you are paying to heat? Might make sense if you are overheating by having a blazing fire in your chimney, but you shouldn't.)