Heating a passive-ish house solely with ducted A2A? No UFH 🤔

[fatgus]

We’re about to start our passive-ish build. Our heatpunk calcs suggest heat loss of 10W/m2, assuming we hit our airtightness target
 

Original plan was for ASHP & UFH downstairs, just some towel radiators upstairs. We’re keen to have some form of cooling too, so we started looking at ducted A2A. It would appear that we could potentially switch to that and eliminate the UFH entirely. Missing out on the warm floors doesn’t bother us at all. In fact, losing the UFH could be a benefit as we’re contemplating a kind of earthen/clay floor (that’s another story entirely).

 

Would love to know what people think? Stupid idea? Or worth pursuing, maybe with an eye on potential “gotchas”? It would be great to hear of any first hand experience…

 

[SteamyTea]

I have lived in a number of places with forced air heating/cooling.

It works well.

It can be combined with the MVRH, and maybe an exhaust air recovery water heating as well.

 

The two downsides are that it can be noisy, so needs to be sized properly, and not just thermally.

The other, more serious problem, is cross talk between rooms via the ductwork.  I know someone who was sitting in his kitchen bitching to his mate about his mental wife.

She heard everything in the bedroom. He got his own bedroom after that, and eventually his own, smaller, house.

You also get some ugly grills in the rooms.

But it can be done and I think all the problems are easily overcome.

[fatgus]

Thanks @SteamyTea

The more I look into it, the more appealing it becomes.

 

Although… 

 

39 minutes ago, SteamyTea said:

I know someone who was sitting in his kitchen bitching to his mate about his mental wife.

She heard everything in the bedroom. He got his own bedroom after that, and eventually his own, smaller, house.

…could be quite a crucial issue to eliminate 😂

 

 

[JohnMo]

10W/m2 ties into passivhaus heating requirements, that can be done via MVHR if you want, but doing any cooling via MVHR is not really that successful.

 

A2A could do both. Do DHW via direct immersion heating. Not really cost effective to do much else with A2A. Even with an ASHP I do direct anyway, not noticed any uplift in electric cost since I changed over.

 

But for primary heat source, buy carefully, do your research as performance can vary hugely. As can the I'm fukced off with air always blowing at me factor.

 

Maybe if doing A2A look at ducted systems.

[JohnMo]

48 minutes ago, SteamyTea said:

The other, more serious problem, is cross talk between rooms via the ductwork.  I know someone who was sitting in his kitchen bitching to his mate about his mental wife.

Or maybe don't do ducted, do wall mounted and no cross talk

[fatgus]

1 hour ago, JohnMo said:

Or maybe don't do ducted, do wall mounted and no cross talk

I’m thinking wall mounted makes sense for the bedrooms then… 

[fatgus]

1 hour ago, JohnMo said:

A2A could do both. Do DHW via direct immersion heating. Not really cost effective to do much else with A2A. Even with an ASHP I do direct anyway, not noticed any uplift in electric cost since I changed over.

I think direct DHW definitely makes sense… we’ll have a decent PV array and batteries, so electricity should be mostly ‘free’ and worst case it’ll be off-peak.

[fatgus]

2 hours ago, JohnMo said:

As can the I'm fukced off with air always blowing at me factor.

That would would indeed be a bad thing 😬