On Wednesday, 4 November 2015 21:35:08 UTC, rick wrote:
On 04/11/2015 19:48, dennis@home wrote:
On 04/11/2015 18:04, rick wrote:
On 03/11/2015 22:47, nt wrote:

I haven't run the numbers but expect you'd be better off all round to
feed
the electric heat into the existing tank. The water wil go above set
point,
and not need other heat sources until the temp is back down again.

Can't do that ... max temp I can have store get to is 60 degree ........
any higher and you risk damage to underfloor heating pipes.

They should have a mixing valve to prevent the floors getting too hot.

No the design has a mixing valve on the DHW take off, but the main feeds
off for the UFH loop is not via a mixing valve ... the main tank stat
prevents it going over 60 degree.

This extra electricity comes at times of high sun output, ie when ufh is not usually being used. So in principle you could add a stat that stops the ufh pump coming on when the cyl is too hot for it. Then you get the benefit of your extra leccy without a bunch of extra costs.


NT