MVHR and cooling

[JohnMo]

5 minutes ago, James Allen said:

We've decided to go fully electric, dimplex for hot water and a few electric radiators

That's different.

[James Allen]

7 minutes ago, Nickfromwales said:

Thanks Nickfromwales what's going on here?? Aircon attached to MVHR?

[Nickfromwales]

33 minutes ago, James Allen said:

Thanks Nickfromwales what's going on here?? Aircon attached to MVHR?

Yup, kinda. Refrigerant gas duct cooler, with external HP, which can heat and cool.

 

If you want cool, it's gotta come from somewhere, so I am more intensively exploring options for these situations atm.

 

There is also the Brink Air Comfort (AHU) but if you don't have a heat pump you're options are very much limited, hence what I showed you in that image.

 

FWIW, I think if you want all electric space heating and cooling, with MVHR, then you'd be far better off going multiple A2A AC throughout.

 

Space heating via electric radiators is pretty poor tbh, unless it's a PH+ spec build, and I think you'll come to regret that imho.

 

I assume there won't be UFH then, so nowhere to implement slab cooling? This is the better option and far less aggressive means of heating and cooling, and imo the most economical operating costs/least impact the occupants.

[JohnMo]

4 minutes ago, Nickfromwales said:

UFH then, so nowhere to implement slab cooling? This is the better option and far less aggressive means of heating and cooling

We had 30 degs yesterday - cool by England standards, but we still pulled 50+kWh of heat out the house by UFH run in cooling mode. Including heating DHW, used all of 11kWh of electric, all provided by the sun FoC via solar PV.

[JohnMo]

1 hour ago, James Allen said:

We've decided to go fully electric, dimplex for hot water and a few electric radiators

What's you heating requirements in kW at -3?

 

If no heating system why not modern storage heaters, this would allow you to run on off peak electricity, to massively reduce running costs. Also if you PV, charge the storage heater with excess PV to make running the heating in shoulder months free or almost.

[Benpointer]

I looked at adding the ComfoPost to our Zehnder MVHR but in the end it seemed like an unnecessary complication and expense since we are going to have UFH anyway and we can run in cooling mode from our Panasonic ASHP.   

 

The need for insulated ducting on the supply side is a big negative imo.

 

It remains to be seen how effectively UFH in cooling mode works for us but it's got to be better than nothing.

[Nickfromwales]

3 minutes ago, Benpointer said:

The need for insulated ducting on the supply side is a big negative imo

The radial stuff comes pre-insulated if you want, so no other issue than the slight uplift in cost.

[SteamyTea]

5 hours ago, JohnMo said:

I would need to increase my MVHR airflow rate by 4 to get 3kW cooling

Which is only doubling the ducting diameter (assuming it is round).

[JohnMo]

1 hour ago, SteamyTea said:

Which is only doubling the ducting diameter (assuming it is round).

And change terminals and possibly the manifolds, and the MVHR unit. So that's easy. All to get 3kW cooling.

 

Then in winter the unit will not turn down enough, so you spend all winter over ventilating.  

 

May as well just do A2A

 

[Marvin]

We find when its really hot the sun is out so we use a mobile air conditioner which has a heat pump. It doesn't do the whole building but then we tend not to be in most of the rooms.  

[Nickfromwales]

1 hour ago, Marvin said:

We find when its really hot the sun is out so we use a mobile air conditioner which has a heat pump. It doesn't do the whole building but then we tend not to be in most of the rooms.  

One that has a whacking great duct that has to go to atmosphere? 180mm on the one in my sons attic room, but it's so cold up there atm that you could keep meat; whilst the rest of us squelch about in the ridiculous heatwave.....

 

No wonder my other kids go and kip up there when the sun finally shows its face.