ASHP and Towel Rails

[Ralph]

We have a couple of towel rails due to go in that run off the as yet to be commissioned ASHP. The towel rails can be dual fuel, Is there any point in adding an electric heating element or will just the ASHP be ok? I'm thinking about the summer months.

Thanks.

[saveasteading]

Ashp radiators are not very hot.

I suggest add an electric element and timer. You just push an on button and it will turn off in 2 hours. Esp good in summer as rads are off.

[Bonner]

In previous houses, I have run several towel rads from a tee before the diverter valve. They come on with both hot water and heating, controlled manually or by TRVs. Simple!

[Nickfromwales]

1 hour ago, Ralph said:

We have a couple of towel rails due to go in that run off the as yet to be commissioned ASHP. The towel rails can be dual fuel, Is there any point in adding an electric heating element or will just the ASHP be ok? I'm thinking about the summer months.

Thanks.

You do NOT want the ASHP firing up just to warm some towels!! That would be hugely inefficient and would cause all sorts of problems with short cycling. ?. 
Put the towel rads on dual fuel elements so they come on with the ASHP any time it’s running heating ( which will help out with smoother running of the ASHP whilst servicing the UFH ) and just bite the bullet on a bit of direct electricity for the summer. 
Do you have PV in the picture?

[joth]

34 minutes ago, Bonner said:

In previous houses, I have run several towel rads from a tee before the diverter valve. They come on with both hot water and heating, controlled manually or by TRVs. Simple!

Bear in mind that if the towel rads are all over the house, and if it's a well insulated house, this could add quite a bit to summer overheating. If you do do that obviously insulate all this extra pipework

 

We decided just to go with electric towel rads, and not plumb them in at all. I have them set to run for 40mins after anyone uses the shower/bath, and remain turned off the rest of the time, to avoid any unnecessary heating.

 

[Nickfromwales]

34 minutes ago, Bonner said:

In previous houses, I have run several towel rads from a tee before the diverter valve. They come on with both hot water and heating, controlled manually or by TRVs. Simple!

That can cause huge problems with balancing a larger system. All of the pump potential looks to escape through the towel rads before servicing the furthest away / most difficult to ‘get to’ rads. It would also slow down the rate of recovery ( how long it takes to reheat a tank full of hot water ) significantly. 
I would not recommend doing that at all if it’s a larger system / family home. 

[Ralph]

28 minutes ago, Nickfromwales said:

You do NOT want the ASHP firing up just to warm some towels!! That would be hugely inefficient and would cause all sorts of problems with short cycling. ?. 
Put the towel rads on dual fuel elements so they come on with the ASHP any time it’s running heating ( which will help out with smoother running of the ASHP whilst servicing the UFH ) and just bite the bullet on a bit of direct electricity for the summer. 
Do you have PV in the picture?

Thanks Nick for the nice and clear response. We don't have PV at the moment.

[SteamyTea]

Keep the room ventilated via the MVHR and the towels will dry quickly, and you will recover a fair slice of the latent heat as the water condensed in the unit.

[Bonner]

1 hour ago, Nickfromwales said:

That can cause huge problems with balancing a larger system. All of the pump potential looks to escape through the towel rads before servicing the furthest away / most difficult to ‘get to’ rads. It would also slow down the rate of recovery ( how long it takes to reheat a tank full of hot water ) significantly. 
I would not recommend doing that at all if it’s a larger system / family home. 

 

Agreed, it could cause balancing issues if not set up right. I had minimal flow through the towel rads restricted by 10mm pipe and lock shield valves. Did not have any impact on radiators or hot water. Just an idea, worked well for me but not for every situation.