JohnMo

This how your manifold works. Can only really be TRV issue. Gone wunda a call, may be covered by warranty.

No - I cut and pasted from your post for consistency in units

It looks to operate in a similar way as a radiator. But with a pump in the middle. So water comes from source to TRV. TRV fully open - hot water goes into pump, through UFH loops and out of the right hand manual valve. At a part open position for TRV, some hot water will flow to pump, the rest of the water will be taken from the return water from the UFH heating loops. So if the loops are not getting hot water, the TRV must be closed more than it should be. Loops like the TRV has a capillary tube, so would suspect either the top rail or TRV end is broken and needs to be replaced. I think the TRV comes as a complete unit, for about £20 to £30.

30 to 40% of electricity is generated by gas, so hike in gas price equals a hike in electric prices. A kW of heat is a kW heat whether gas or electric is used, unless you use heat pump, buts another story. We are paying Gas kWh-1 is £0.0402 Electric kWh-1 is £0.20 Electric combi running costs would be 4 or 5 X as much for the same quantity of hot water. Also a gas boiler can give 30 plus kW at the water instantly, what can an electric combi do? A quick look for £1k it's 7 to 12kW and about 4 l/m DHW flow rate. For same boiler cost we get 15 l/m from gas. If you want to go electric, a Unvented cylinder and E7 or heat pump, make sense.

Photo of my combi set up. Thermal store upstream of combi. Cold water is connected to DHW coil, and is preheated prior to going into Atag combi. Winter, combi central heating circuit connected to closed loop heating coil, acting a UFH buffer, UFH connected to thermal store. Thermostat limits boiler heating of thermal store to 40 degs half way up cylinder. If there is excess solar PV, this heats boiler immersion. Summer, heating side of boiler off. PV excess to immersion. Immersion set to 75 deg. Temperature of cold Water feed to boiler limited to 55 degs by thermal store mixing valve. Atag boilers can take preheated water.

I would question the pricing you are being quoted, our floor is insulated with 2x100mm and the material cost was £3500. Floor area is 190m2

A floor temp of 27 degrees will not be comfortable to walk on

Would start with manifold temp at high 20s if the thermostat setting is never reach tweek up a degree or 2. If you are over shooting the thermostat tweek down a degree or 2, repeat over a few days until you meet the thermostat temp with out overshoot more than a degree. Leave about 24 hrs between setting changed

Just got lots of holes to fill and paint, but that's a job for the new year.

It's bit like weather compensation, if your house is badly insulated it works great, same with all the bells and whistles thermostats. A well insulated house with a fair bit of thermal lag, they just make things complicated, with no real benefit. I had thermostats in all rooms, weather compensation, they were all removed when we started using the heating: as the heating was all over the place. Now have one thermostat in the hall, spent a few days tweeking UFH water temperature, get the right degree of room temperature under/overshoot. The whole house sits at 20 deg (+/-0.5), except bedrooms which at 17 to 18 degs (,cool bedrooms is a choice made at design stage). Now run same temp 24/7.

Yes had to parge coat Durisol to get airtight. (2 days additional work). Was never wet inside, except where water came in unsealed openings prior to door and windows. Started the walls end November, so had full winter open to elements. The open structure of woodcrete, means no ill effects of water does hit the walls. A major plus for me was not needing much in the way of reinforcement, either structural or to do the concrete pour. So made easier to build for me. Just osb screwed to corners and at lintels, prior to pour, removed 2 days later. You can screw things direct to woodcrete, like device battons. Half of our house is wooden clad, so building wrap, made this watertight, the other half was only finished stone cladding last month, internal of house finished a couple of months before this. All have their advantages and disadvantages. Would use Durisol again, the installation manual is user friendly, but suspect most are. Built mine when courses were not being offered due to COVID and still found it quite straightforward. From start to finish, 190m2 with up to 4m walls, 2 people 40ish hours week, 4 weeks. Support from factory and local rep when needed. Cost around £60 / m2, ready for the roof and windows.

Lots of hidden costs they don't speak about. Maintenance costs can be huge compared to traditional generation Example a coolant pump for a gas powered station is £xxxxx, the pump for nuclear has many changes in spec, which can double or more the cost. Installed life is reduced due to safety implementation of failure in service. Loads of extra safety measures that are not applicable elsewhere, which means productive manhours are very low also. Then there's the decommissioning cost, which the tax payer picks up.

With Durisol, you do 6 rows then pour., So rear of house had 2 pours and front 3. But only had the cement pump twice. Front of house had lots of fiddly bits, so first pour there was done by bucket.

Forgot cost all in including a wage for no 2 man, was just under £12k

I went Durisol route., Was building wall in November/December last year. No down time due to weather, can pour concrete at -6 deg I believe. You don't need as much rebar as other ICF systems. 2 of us working 5 days a week, took 4 weeks to build our walls. 70m long, 2.5m high at rear, 3.5 to 4m at front. Structurally complete and fully insulated. Never done it before, I am not a builder. Stone slips attached straight to Durisol. Timber cladding external battons screw into Durisol. Same with internal battons. Parge coat inside walls for airtightness.

I think and someone will correct me. Blinding sand DPM. Insulation, on DPM and up the wall. (25-50mm up wall). If using aluminium faced board, a polythene interface layer. UFH pipes Concrete floor. As said 50mm insulation is not enough. If you can 150mm that is better. Otherwise the heat will travel down as much as upwards.

We had no cooker hood for about 6 weeks, no issue with smells etc, but we didn't fry. If you are frying you need something to extract the grease that become airborne. Otherwise you will be trying to clean your ducts to the MVHR in a year or so. You also need a filter in the mvhr duct to catch the grease the cooker hood doesn't extract.

Never had that issue, last house was 200 years old and part of the roof recovered 10 years ago. Latest house has good quality slates and not seen any issues either.

Depends how thick they are, in Scotland they are specified thicker than in England I believe due to higher wind loads. Our are 8 to 10mm thick. Walk around a 5 or so year old building development near you, to assess what concrete tiles look like, do the same with any slate buildings. Around us the concrete ones tend to have faded and have Moss on them. But that could be our weather etc. (NE Scotland)

Long post. So cold water that feeds the boiler in the loft is taking the easiest route to come out of the cold taps, instead of the more restrictive route into the loft where you have the boiler. Your boiler will not support a UVC as it's a combi. The flow rate may not support more than one shower at a time, unless they have restricted flow. Have a read of the attached to get an idea of what you can do to improve what you have. A plumber will need to jump in on how to balance your flows. Canetis-SuperFlow-Product-Sheet-WE-050318.pdf Combi-SuperFlow-White-Paper-v1-2-4.pdf

Link is about heat exchangers?

Others have done bead insulation, injected into cavity, but not sure if this is an option? dMEV is low on the expense side as you will utilise the existing holes in the walls and wiring. But you don't get the advantage of heat recovery. If you see heat recovery as a must the next thing up would be decentralised MVHR, where a unit takes in fresh air and extracts through the same hole, something like this (quite few different makes are available) is very condition based ventilation. https://ecostream.org.uk/products/

Combi is fine, but if using a combi, look at installing a combi Superflow with it. Have attached some reading material. The other route would be system boiler with UVC. But remember insulation and draft proofing should be your first things to sort out. That will give you the best payback, windows would be much lower on my list of priorities, unless they are single glazed. You should also look at your ventilation strategy. You have possibly got fans that come on wet rooms when you switch on the light, then make a loads of noise for 10 mins. The next thing up is dMEV, always running in the background, but very quietly and very low electrical usage. These fans replace the existing ones, so easy to install. Combi-SuperFlow-White-Paper-v1-2-4.pdf Canetis-SuperFlow-Product-Sheet-WE-050318.pdf

Look up the history of Durisol, they are the first ICF block, been around since the 1940s. There's a good photo on the internet, where a hurricane hit and the only building standing was a Durisol build house.

Mine was supplied by the floor installer, like hollow foam box with a digital gauge. Stuck it to the floor for 24 hours.