Fan Coil Units for use with a (cooling) ASHP

[saveasteading]

23 minutes ago, JohnMo said:

soak aways are huge, compared to normal

I'm interested.

The regs show ever bigger areas where permeability is poor.

On sand they don't seem to acknowledge that the water won't reach the end. 

 

So in our case we used perforated pipes heading different directions to spread it.... phase 2 and 3 extensions to the zone, the drawings and calcs got us the approval, but are 'yet' to go in.

[joth]

23 minutes ago, JohnMo said:

Set up to run long run for periods, this helps a lot. Plus our ambient outside helps. 

And down-sizing the ASHP to allow these long runs at a low  deltaT without short cycling, isn't it?
Our ASHP is way oversized so will bordering short cycle (5 min runtime, 10min period) when just cooling the slab to ~16deg.

I'm still getting COP of 3.5-4. But it's powered from PV - if I could double the COP it would give me about 30p more SEG payments per day on these hottest days.  

 

[JohnMo]

5 minutes ago, joth said:

And down-sizing the ASHP to allow these long runs at a low  deltaT without short cycling, isn't it?
Our ASHP is way oversized so will bordering short cycle (5 min runtime, 10min period) when just cooling the slab to ~16deg.

I'm still getting COP of 3.5-4. But it's powered from PV - if I could double the COP it would give me about 30p more SEG payments per day on these hottest days.  

 

Last year on our 6kW heat pump it cycled, depending on load, we averaged around 4 to 5 CoP over the day depending on a few factors doing cooling. This year with a 4kW it can run low and slow, our dT was about 2.5 degs. Yesterday's whole day CoP was 7.3 including standby time/energy.

 

We only cool if there is solar gains, so we have plenty of PV also. So it free. It would almost always get clipped from PV also, if we weren't using it, so it really is free.