u/Jay638

Hi folks, 330m2 house, 1980 build with various upgrades over the years including blown cavity filling, loft roll, loft extension with 100mm celotex everywhere, UFH through half of downstairs with 50mm celotex below..

I've had 3 heat losses done now; a HeatGeek trained installer 11.5kw (proposed 12/13kw Ecoden @ £14k total), local installer 12.2kw (proposed Grant 12kw @ £11k total), Octopus 13.9kw (still haven't quoted due to complexities of the install).

Heat losses were done to 21c (HG) 19c (local) and I'm not sure with Octopus at -3 outside. Flow temps 55c (HG), 48c (local installer) and 50c (Octopus).

I think we are going to go with the local installer and the Grant Aerona R290 12kw. We are right on the cusp re heat loss, but I really don't want to oversize and would rather add more insulation I think if I have any problems. Q1- Is this a sensible approach? Or am I risking a cold house?

On buffers, they've offered 50/75 and 100. I've asked for as small as possible. At 50l we are right on the limit for minimum volume when all zones are closed Q2- Should I do 50 or 75L buffer?

Zoning - We are currently 3 UFH (downstairs) and 2 heating zones (down and up). All radiators have TRVs. Q3- Should I go one big open zone, or keep the zoning. Installers' views have differed on this.

Includes a new 300L cylinder. I’ve got a couple rad changes to do myself.

Many thanks for the help!!

Hi folks - amazing work here thank you.

Is anyone using a MyEnergi Zappi (v2) and if so does it work in exactly the same way as with Octopus?

I noticed on IOG over the years that from time to time the Zappi would not charge the car in a given smart off-peak slot, eg because Zappi had applied a 10 minute grid delay and it was a short slot, however the off peak sesnsor would still be "ON" and I was still always charged the off-peak rate in that half-hour, despite the car not getting any KWs.

Presumably that's the same on EDF? But wondering as if not I will need to find some way of confirming the car is actually charging before I switch on battery charging for my home etc. for fear that off peak slots could retrospectivly become peak slots because the car didn't charge.

Any perspective welcome. Cheers.

Hi folks, I’ve spent ages looking into this with no joy so any help appreciated.

I’m after a 300L HP compatible cylinder, so with a very large coil area for the HP.
Theres several manufacturers, but all the cylinders I can find are for unvented hot water.

I don’t want an unvented system as there is large demand (3 pumped showers + sinks) and a new huge CW storage tank in the loft and no desire to become dependent on street pressure/flow rates nor easy way of getting 22mm supply plus drain etc etc to the cylinder location. Cylinder supply is 28mm but only 15mm to loft CW tank.

I could use an unvented cylinder and just vent off the top, then downward tee for the showers but then I have a flow restriction as 22mm take off and no option to use an S flange to help deal with air.

Ideas would be appreciated, thanks!