ProDave

My plumber did not think so. He did not even ask if my ASHP had a backup heater. He just expected the cylinder thermostat so shut the motorised valve feeding the tank. Perhaps he is just a typical old school plumber and cannot understand the difference between a 5kW ASHP and a 20kW gas boiler. Perhaps more modern plumbers would not insist on that?

The safety feature is one of the things the plumber checked before giving me G3 signoff. You might argue an ASHP cannot possibly heat the water anywhere near boiling, but my ASHP as a 3kW backup heater inside it and a possible fault condition is that gets stuck on. In normal use, my tank does not use the traditional tank thermostat. It has it's own temperature probe in a thermostat pocket. The traditional tank thermostat is only there to shut off the 2 port valve if the tank goes over temperature, and the temperature it is set to is much higher than the normal tank operating temperature.

To clarify if everyone is making the right diagnosis, can you post some pictures of the plumbing, in particular what motorised valves you have, both general views and close up views so we can read the model numbers. My preference is not to allow a 3 port valve into my house. I much prefer 2 or more 2 port valves. But basically an ASHP should NEVER fo heating and DWH at the same time. It is always one or the other. That does not mean you have to set the programmer so they are on at different times. Usually when both are on, DHW will be priority, so when the tank needs some heat, it will stop heating the house. My own LG ASHP will set time limits on how long it will spend at a time doing DHW if you think there is any chance of the house cooling down while it is heating the DHW.

Hi and welcome. Your plan there is on the right lines. As you have already identified, the key to success is good detailing. So well fitting panels of insulation fitted and all imperfections filled with foam and taped. As to is an additional 25mm enough, many would argue not enough. How much celiing height can you afford to lose? 50mm would be better. But whatever you do will be vastly better than nothing. Re detailing the plasterboard when finished. Look at dry lining it aka tape and fill. You only fill the edges and joints between plasterboard and screw heads. I am the first to admit I have tried and failed miserably at plastering, but I can tape and fill a wall quite reasonably and can give my opinion on what products are good. Out of interest how old is the house to have been built like that?

That is very disappointing to hear it is not as described. Do keep us posted.

Screw the discussed L shaped bracket to the wall into each stud, and then down through the L shaped bracket into that cross bar at the top of the unit. What is so difficult?

Standard practice to fit dwangs (noggins) at just below worktop height and top of wall unit height before fitting plasterboard for that very reason.

Is this liability insurance for a self build site you can't get? Or a structural warranty for the building?

Your reed switch is rated at 1 amp. Your light driver is rated at 0.65 amp. So in theory you might be okay. BUT that will be a switch mode power supply so the input circuit us usually a bridge rectifier then a smoothing capacitor. So on first power up there will be a high starting current to charge the capacitor quickly. It is likely that high starting current has welded the contacts of the reed switch. Seriously, i would look at a little mechanical switch of the type used for limit switches on machinery that will be activated when the gate gets to end of travel. Or hack the existing circuit to find a way of triggering a relay from the existing switch. Do you have a picture of the insides of the controller?

Assuming these are tall so you can't look down on them. Screw an L shaped bracket to the wall at each side, dead level with the top cross member on each cabinet. Put the cabinet in place, a single screw down through the L shaped bracket into the cross piece at the top of the unit.

That just strikes me of a lousy design.

And the repaired section of the bank completed. Land drain pipe still flowing.

No that is too specific. Yours is a make it up as you go along box of terminals for a one off system.

The varilight one is something altogether different.

No, that is what you would use if you were having lots of individual zones and individual actuators for each pipe loop. You just want to join together the two motorised valve cables, 2 thermostat cables, a cable to the pump, a flex in providing power and (still to be determined) how to connect to the RTC6. Something like this https://www.toolstation.com/drayton-wiring-centre/p56309

Good find, but THE PRICE !!!!

To make it work you need a junction box to connect it all together, I would start with a standard central heating "wiring centre" which is usually just a plastic box with a 12 way terminal block inside and lots of cable entries. I am hoping that one of the many forum members familliar with the FTC6 will answer what it's call for heat input is.

So you have one motorised valve per manifold but only ONE pump that serves both manifolds. That complicates the issue. What is the call for heat input on the FTC6? Does it have to be a volt free contact or will it accept a switched 240v ac input? The logic is: Basement thermostat energises basement motorised valve when it wants heat. Ground floor thermostat energised ground floor motorised valve when it wants heat. The feedback contacts (orange and grey wires) from both motorised valves connect in parallel and will turn on the pump when either floor is calling for heat. Where it will get complicated if the FTC6 insists on a volt free contact you will have to use a relay.

Yes you want to specify "loop at switch" Wiring regs don't specify which method to use, it is choice of the electrician or the client.

If anything I would say mine defrosts more in DHW mode as it is generally working harder then.

The worst time for icing is when the air is a few degrees above freezing, the heat exchanger will be colder and in this case below 0. Once the air gets below 0 for any length of time there is little moisture left in it, so almost counter intuitive, there is much less chance of icing. I have an older version of the monoblock ASHP and there are no user adjustable parameters relating to defrosting. And nothing published about how it decides when to defrost. I would be inclined to just let yours get on with it if nothing else to see if the defrost function works.

4 gang grid switch is your only answer with one fitted with a blank. I have never seen a 3 gang switch in a 2G wide front plate. Or if going for new dimmers, just buy any make of new dimmer and swap the modules over onto your old front plate.

My No 1 tip is do it as a warm roof or hybrid roof. So air tight layer over the top of the attic joists (roof stripped completely) external insulation over the top of the joists, then batten counter batten and tiles or do the rolls royce and an in roof PV system. Take the insulation right down to the eaves don't faff about trying to exclude the eaves space from the insulated envelope. You might want a SE to check the existing attic trusses are ok for a heavier roof tile and PV.

I thought the conversion from m3/m2 to ACH was very approximately 1:1 but there is no simple universal conversion because it depends on the geometry of the house, i.e is it single storey, 2 storey, vaulted ceilings etc. If it really was divide by 20 them my 1.4 m3/m2 would be 0.07ACH. No way is that the case.

And sometimes it can be warmer here due to the Foehn effect