JohnMo

Our last house was originally built in 1830, some insulation improving done but not much. It was a heat sieve, we never had bedrooms heated, our bedroom window was open 360 days a year, a few very cold nights closed.

You use, the Daily heat loss power for min OAT the coldest day. In thee example below for Jan. So that gives you the total heat loss for your house. No. Total heat loss is total heat loss, if this is supplied by 100 or 1 heater it's still the same.

Sounds like the ventilation rates are not that good. If correctly set the air in the bedrooms should always feel fresh. We do get hot in our bedroom, so we just open the window as we feel. Our heating or ventilation doesn't get touched on a day to day basis. In fact ventilation doesn't ever get touched.

What's so special about them except the huge price?

£360 per panel

Exactly, the Passivhaus article above makes that direct reference. Our I stipulated the height, the installer did what they always do, set it 200mm higher than I stipulated. Didn't pay the final invoice until sorted at their expense - which they did.

I was thinking more like £5 over 10 - 20 years, that whole area needs to be insulated anyway, so no real thermal bridge exists anyway.

So your insulation is on top of the rafters? That whole area will need to packed with insulation anyway, so still confused where any size of thermal bridge exists.

Are using solid metal pipe? If so you will need cross talk attenuators

Not sure it can, there is a swinging flap that closes one port - the other port open, as the flap is driven to close a port the other port opens, most the transition two ports are open. Done two interlinked 2 ports would stop flow. Nothing wrong with a 3 port valve, they use the same actuator as as 2 port, so all the midpoint reliability issues are not present.

Do my jacket pots the same way, in microwave for 2 pots for 10 mins, in air fryer for 20 to 30min.

I am confused what thermal bridge you are trying to fix. Are they really? How is your roof insulated?

Funny you say that the was a comparison done in a football ground, where they installed an industrial sized air fryer. The air fryer chips didn't go down any worse than the traditional oil fried chips in a blind test with the football fans. As I said took a long time to be converted but if you like crispy chips they are great.

I really wouldn't worry the restriction is for a very short length. I heat my cylinder via 22mm primary to a 28mm Honeywell diverter with no issues from a 6kW ASHP. Your cylinder may come with a diverter - mine did, so worth a check

Make sure the diameter isn't an access issue, if you are going through a loft hatch

Get an air fryer - way better chips. Took me awhile to be converted

Prices were on there way down prior to COVID, then prices shot up with the shortfall in production, prices are now reducing again. Trouble with PV the models of the panels keep changing, the prices fluctuate a lot. End of line stock will always be cheaper, same as slightly lower performance panels. Wait you maybe ok, wait you may not, who knows.

I did and it's included in another recent thread. As @Nickfromwales says payback is a life time or two. With a heat pump something like 50 to 140 years depending on the tariff and how much you actually loose from a standard cylinder when water is stored at below 50 degs and how much you pay for a cylinder. I did add into this the loss of CoP as the full recharge has to be completed at full temperature instead a slow ramp to full temp for a new cylinder. Bonkers idea

But you say at the start of the thread your thermostat makes the boiler run in weather compensation. The idea is with weather compensation is the heating system just gives enough heat to the house to maintain the house temperature. The boiler runs for very long periods. So in theory the zone valves should never close. You are referring to a heating system that runs at very high temperature with on off controls. So in that case the boiler would fire for a short period, the thermostat says the room is hot enough, switch boiler off temperature in the rooms drops, boiler fired up, repeat.

As above, so you have zero need for any zones valves with a combi. Just run as a single zone.

A close coupled tee can be anywhere in a circuit, but you just need to ensure you have flow to the CCT and back to the boiler. I operate two zone one is the house UFH and the other is a summerhouse with fan coil. Both have a thermostat and can call for heat but both have to no longer require heat to shut off the heat pump. I run without any zone valves. If the summer house needs heat the floor of the house is also heated (acting as a buffer). In the last couple of months the house hasn't had to call for heat, as it's always hot enough just because the summer house is calling for heat more often than the house. Energy consumption isn't affected much in fact it's quite good. My buffer, electronic mixer are being removed soon. So it will be ASHP, fan coil and UFH all driven from ASHP pump, two thermostats, either can call for heat, both off to stop heat. So to simplify your system. You run WC, is there any real need for zone valves at all, what do they do (DHW and heating)? Just run long and slow as WC is intended? Your UFH will just need a mixer/pump to drop flow temp down to a suitable level. Leave it to run all the time. Apply KISS to your thinking go back to what you need as a minimum, remove the complication.

I have one and still have the gas boiler installed, although I do use an ASHP. But really hope they do stay banned.

Another thing missed in the article is the notional building performance has been moved to a higher standard also. So mediocre designs are pretty much banned, without loads of solar to compensate.

Not quite "Other ZDEHS solutions include: • 100% Hydrogen – the use of 100% hydrogen is the only current example of a fuel which, when combusted to produce heat, results in negligible levels of greenhouse gas emissions."

Yes referred to phe pump, not sure if the advantage but that's two companies that do. This what my manual says about DHW heating. There is some modulation but not until 1 Deg of target temp. My Atag boiler seemed to operate exactly the same as the heat pump, I noticed if you tried to heat a cylinder (thermal store with heating coil) at too low a set temperature against small coil, it just wouldn't get there instead it would just cycle a lot. Cylinder temperature would remain static, boiler would run for a minute overshoot target and shutdown for 10 mins. I over came the issue with a huge PHE.