Air Source HP, UFH & Screed

BarneyMc

It seems like the conventional way to work an air source heat pump is to let it run at night on half price electricity.

When it's doing this does it have to 'charge' the slab at the same time, i.e. does the UFH have to be working at night too so the slab is warm for the next day? In this case a 75-100mm concrete screed might be suitable?

Alternatively, can the HP be used at night to heat the water which can then be sent around the UFH pipes sometime the next day? In this case a 35-50mm liquid screed might be suitable?

mapboy

When the heat pump is running at night it heats the buffer tank. The water in this tank will only be used if your heating zones call for it. This tank is able to store water for a long period of time with a slight temp drop.

I went with the 40mm liquid screed. Got loads of advice and also went see systems and they seemed to perform well.

Tommyboy08

mapboy wrote: »

When the heat pump is running at night it heats the buffer tank. The water in this tank will only be used if your heating zones call for it. This tank is able to store water for a long period of time with a slight temp drop.

I went with the 40mm liquid screed. Got loads of advice and also went see systems and they seemed to perform well.

Your buffer tank must be massive to have the ability to be heated at night to keep an underfloor system supplied all day, what size is the buffer and what temp

BarneyMc

If not using a buffer tank then does that mean when the HP is running it is also circulating the warmed water around the UFH system?

froshtyv

BarneyMc wrote: »

If not using a buffer tank then does that mean when the HP is running it is also circulating the warmed water around the UFH system?

The heat pump should only come on if you have a thermostat calling for heat in an area of your house.

The idea with using it at night is, cheaper electricity costs, and to reduce the running time of the heat pump during the day.

If you "charge" your slab at night, depending on the insulation level/ air tightness of your house, you might only loose 1 degrees during the day. So if your thermostats are still satisfied your heat pump wont run again until the following night.

It can also be timed to do your DHW an night.

Ros1234

I'm going down the route of A2W HP with no solar.

I'm trying to figure out which of the following options is best;

1) Heating the house by day (higher outside temp) at standard rate ESB (don't bother with night time rates as I'm told this increases the day time rate)

or

2) Going with night time rate and heating the house at night, but then the outside temp is lower thus the HP is not as efficient so running longer.

I'm leaning towards option 1, any advice would be welcome.

Cheers

BarneyMc

Like the last poster (Ros1234) I'd like to hear which way others went and if it is working out for them.

I just can't get my head around how a HP can work at night without going the thicker, sand & cement option.