JohnMo

Daft question, is the pre build one or as built post build. I made lots of changes to the as-built one to make sure thermal bridging wasn't generic etc. likes other have done. In the end it seems to a fairly close, on a monthly average basis. Although I don't recall seeing what the actual heat loss was on the coldest design day. Just monthly averages, which may not be that useful for heat pump sizing. Jeremy's tool may be better.

My heat demand is 14 W/m2 of the top of head. My spacing is 300mm, flow temps is about 27. The delta T of 10 isn't realistic it's likely to 4 or lower at those flow temps. High delta T means lower input of heat into the floor for a given flow temp, as the mean flow temp is lower. The higher the flow temperature the more likely the room temperature will overshoot. So it's all a bit of a suck and see and a balance trade off. Also floor finish has quite a big influence. So what correct in one room may need tweeking in another by changing the delta T.

Sorry miss read. No you don't take into account the flue pipes, although I assume you have room sealed stoves, with an outside air supply direct to the stove, not air bricks to provide the combustion air.

If the two manifold pumps have a mixer upstream, then there is hydraulic sepereration, so the pumps then have no interaction with each other. The manifold pumps pull the water through the mixer. The main system pump delivers flow to the mixers.

Are they stove connected ie sealed to the stove and open in the room?

If it arrives today I will be installing an Ivar mixer (to get a better control of flow temp), so may well give that a try also.

Interesting, you don't use the flow meter or have them all fully open?

I would do Fresh-R, or similar, if I ever did it again. Hardly any ducts to run, on demand ventilation, reduced number of air changes, if the house doesn't need it.

Not the best spreadsheet for calculations. Basically balance supply and extract. Here is some guidance on flow rates. It's a bit of a giggle to get thing matched up. I found it easier to build my own sheet.

Tell that to the numpty politicians all flying in their private jets to COP every year. It all nonsense that could, should, be done via video conferencing from their own countries.

You could do what they show or staple. Use Pert-al-pert pipe as it is easy to form, straightens easily and bends well by hand.

Cold ran down from Manifold, under the floor, then up at the point where the sink was going to be. Photos of stop cock and cold manifold. Plant room is in an upstairs loft section, so main water goes there also. Other photo you can see various white pipes coming up at the outside walls. Hot pipes are in the ceiling and drop down. Walls were all battened to form service gap the plasterboarded

I purchased all my UFH kit from Outsourced energy. Just buy what you need. The floor would be quicker to heat in a thin screed, but only if the insulation is directly below the screed, if it has to heat up the concrete below also it will be no quicker than in the concrete. UFH isn't a radiators system it is slow, suits a heat pump as it can used at very low temperature for a long period. Many on here have directly attached to the mesh. Not really understanding Kore's statement on the mesh being structural as that has nothing to do with the UFH pipes. UFH seems complicated when you first look at it. But is quite simple when you actually get into the nuts and bolts of it. Download a free copy of loopcad. That will develop a plan for you to give to the plumber. Your piping centers can be just about anything you like, I did 300mm, most do 150-200mm. Do loops no more than 100m long. Once you have a plan, you will have piping quantity, number of loops for you manifold etc. Get a low temp mixer/pump such as an Ivar.

I put the cold below the insulation and used a plumbing manifold in a central point. Used Pert-Al- Pert pipes in conduit,so the can be removed as per building regs. Didn't do hot in floor, but would do that within the insulation, as above.

I considered using Prana dMVHR, single unit through wall, automated and looks well made

Why limit to just those manufacturers?

Not wanting to do your project for you, but point you in directions where you can research. You need to build an index of topics you need to cover to justify MVHR, steps to design, choices for the design and implementation, costs 'v' cost savings etc. You will need to know each circuit pressure drop, what noise suppression you need and MVHR unit size you would select, what features the unit will incorporate and if boost will be automated or manual, reasons why any cost and/or user implications. If automated on humidity, what downsides there are in a UK climate and high summer time humidity and how to overcome. If manual what is a user never boosts what impacts on the building fabric. Also look at the UK implications of low internal humidity resulting from MVHR in the winter. Is this an issue in the UK or is it more a cold climate thing. Look at the Passivhaus Institute, building regulations, for the country where your house is sited. There is also plenty of information on this site. You should also demonstrate how your flow rates compare to house volume and overall air changes per hour. Comparing building regs with something like Passivhaus guidelines. Advantage/diadvantages of various system configurations dMVHR, MVHR and hybrids between the two such as Fresh-R. Again look at costs, ease of implementation of new build and retrofit.

But should we concentrate on what is in our control the building we live in and potentially building other people are renovating or building from new. By giving sound, well thought through alternatives, to standard building regs levels of insulation and airtightness etc. Hydro have a number issues never really discussed, like anaerobic decomposition of everything the water has covered, emitting methane for example, which is way worse than CO2.

There are windows, doors, ventilation heat losses also. Interesting your house is 38% the size of mine, yet our heating consumption is 42% of yours. So your heating demand could be 4000 x 38% = 1520kWh per year, so about 80+% better. This also equates to about 1kW heating demand at -5 degC. So would only need heating on the coldest days. So not seeing why you can't make the savings, people convert existing housing stock to passivhaus standards, which is better again. But it takes work. Instead you stand saying look at me, I have installed a heat pump, I saved the planet. Insulation, airtightness and general energy reduction by decreased heat loss is the topic you should be pushing! That is what we need, a real reduction in primary energy usage.

This where I bought most of my parts Seem quite good prices and was good service. They do Iver mixers and manifolds

Would look like you have a big satellite dish in your living room tracking your every move. What would happen if two of you walked in different direction?

So your max heat demand in w/m2 is 1541/144=say 11w/m2 Using the attached you get the flow temp you need, but the chart needs extending downwards, mean flow temps are low/mid 20s. That is to balance heat loss with heat input. If you want to blast heat and use a thermostat just add a couple of extra degrees.

Just go on to eBay and type MVHR, there's loads on there for good prices. I have a similar system and layout to you with two systems. Keep it simple, manual boost switches, you don't need £500 of CO2 sensor. Just a boost switch outside each wetroom and in kitchen.

Not sure you are completely correct. You are assuming the heater has to be electric, but the ones @Dan F references are water filled. Designed to take hot water and cold water also, so can equally apply to a heat pump as much as any other cold or hot water source. Quite a few manufacturer out there doing a similar thing, as mentioned early nothing new. Would agree electric ones not as good as a heat pump heating system.

You could do similar to Mixergy cylinder and not have an internal coil, but use a PHE and pump.