JohnMo

DHW priority let's the boiler run at two different temperatures, hot for the cylinder heating, warm for weather compensation. I am currently putting 0.5kW into the floor of our house with 36kW boiler. Your demand will never be that low with an older house. Your boiler will turn down to about 10kW, but if you only want to heat part of the house you may need a buffer. This will soak up excess heat, the boiler eventually trip on excess return temp, the heating will continue extracting heat from the buffer, a period of time later the boiler will kick in. You may only need a 25-50l buffer, pipe as a 2-port, you don't need a thermostat on the buffer if you use WC. You don't need a second boiler, that could be a world of pain depending on your gas meter and pipe sizes.

So they come with roughly the same u value, one is cheap, one isn't, your money your choice

Strange I was looking looking at some left over bits and pieces from the build the other day. Both have been exposed to the same weather and fully exposed outside for two years. OSB has has gone grey, other than that looks fine. External Plywood delaminated very badly and very twisted.

Read my post above - thermolite are nearly twice as good as marmox. Plus if your screed thickness is greater than 65mm thick, there is still a thermal bridge below the marmox block as it doesn't overlap on to the insulation.

No you need to compare as built, with as built. If I had done what the architect had suggested, the performance would not of been as good as the final solution, which was also easier and way cheaper to install.

Not correct, from the marmox data sheet. 0.065m/0.078W/mK = 0.8mK/W convert to U value, 1/0.8=1.25 From the other datasheet 0.215/.15 W/mK = 1.43mK/W convert to U value, 1/1.43=0.7 Thermolite is in fact nearly twice as good for reducing the heat loss, even with a worse conductivity. Because they are 215mm high compared to 65mm. It's the size that matters!

Yes. Pump wear when stop and starting, very little wear in steady state running. They do consume energy but a modern pump is in the range 10-30w.

Yes. Setback the local controller will have that built in, as one of the Target temperatures. Not sure if how they do it?

My original plan was marmox, but when I did quite a few calculations comparing to thermolite, I chose thermolite.

Basically set your system to run on weather compensation mode. Your thermostats become limit stops. So set slightly higher temp than you want. You will need to set the WC curve and flow temp. Basically keep turning the flow temp down until most the house is always the temp you want. The thermostats should not be made to control. Rooms that are to warm, decrease the loop flow, room to hot the opposite. Set a nighttime set back of a couple of degrees.

I totally agree. Sorry obviously I wasn't clear - the Master bedroom is on its own loop. Master bedroom ES on a separate loop. For the reason you state.

Do you have two immersions, have PV connected to say the bottom and a mains one operated by timer/thermostat at the top. Or could you add a Willis heater, to do the job they were designed for, connected to either PV or the mains. Then you could operate the two immersion system independently of each other.

My layout, for comparison, managed to find a photo, similar layout of house (single storey) and floor area from the looks of it. But 200mm PIR in floor instead of 150mm. Bathroom, hall by front door and kitchen diner on a single loop around 100m long. Lounge 2 loops each 100m long ish. Bedrooms single loop each. Master bedroom ensuite single loop, pretty short. Circa 12 l/min flow rate.

I take it your flow temps are quite high, looks like you could reduce and get a gain in CoP?

The distribution box - plenum chamber cancels out any cross talk.

I found with a thick concrete floor screed, 100mm plus thick, that my heating runs with around 6 hour delay. So much so that nighttime setback starts at 1730 and finishes at 0130. I am running with a flow temp at the moment of about 23 to 26 and have 300mm UFH pipe spacing. Could you operate the two manifolds as a single manifold with a suitable sized single pump. Have a temperature mixing valve upstream (more as an insurance policy, to limit max temp) This basically how mine is running. For me there is way to much pipe in the floor, but seems to what people like to do. (I did 300mm centres, so have 400m in 192m2 on 7 loops), have no dedicated loops in halls, but all room loops go through the hall so I just spread them out throughout the floor. But this will depend on heat load required, to some extent. Don't like pipes under walls , to easy for a numpty to put a drill through a pipe.

Sorry not really agreeing. Areas referred to as zones are loops not zones. T5A, 6A and 7A, operate as a single zone, from a single thermostat they will be the same temperature even if you don't want them to be. Do this as a wireless thermostat so you can position where it reflects the temp you want best. But ideally thermostats should be limit stops on temperature, not temperature control. They are set 1 or 2 degrees higher than your ideal temp. Flow temp settings balancing is used to achieve the room temp. So basically you operate as a single zone to ensure your min flow requirements of the ASHP always met or exceeded. In a 150mm concrete/ screed room internal optimisation will not work, system inertia will be too slow, heating will chase it's self, temps will be all over the place. You could do weather compensation as long as works on a 24hr rolling average outside temperature. With that much pipe in the floor I doubt you will need a buffer, if the ASHP is sized correctly. A buffer is used to mitigate too little flow not too much.

Glassloc-system-instructions.pdf

I have attached instructions and test certificate that details deflects at huge loads it also details the fixing used in the test. The supplier is talking out of his **** 1507-1-GlasslocFixing-and-Wind-Load-Data_0.pdf

That's not standby - that's warming up. Why it takes 12 hours is bonkers and doesn't sound realistic. What does the operation manual say?

Put it on weather compensation so it runs all the time, set the flow temp as low as you can, should give a good CoP and no standby. At setback 2 degrees.

I put my strainer immediately upstream of the prv. Stop cock, check valve, outside tap, strainer, prv to the house.

Wait till next April - they may want an arm and leg also.

We have down-lights, but I am not a fan of loads of small ones. We have 6 big ones in the kitchen about 150/200mm dia, fill the room with light little or no shadows. They are flat and white, so disappear in to the ceiling. Look more like a light tunnel. We have a ceiling that follows the roof line, and selected them as they are only about 20-30mm deep. Used slightly smaller ones the hall and most other rooms.

You need to do your research, as the yield in winter is pretty rubbish. You will be able to do DHW in the summer , but maybe not the heating. Really depends on array size and how well insulated your are. Big array, you may be ok on a sunny day for a couple of hours, but would make sure your ok paying full price electric.