JohnMo

I have two Titon units, but found the same units are sold and rebranded by Beam for lower prices. Also found the technical response from Titon was great, when I asked for technical assistance. The unit I bought from eBay for super cheap prices, had a failed motor speed sensor, parts to fix where with me the next day. Can't fault that.

I am taking the meter reading, popping it in to OVO (my gas supplier) app, this give me an exact metered and calorific value converted kWh consumption since last meter read. I have an energy meter at the UFH, it measures, flow rate and supply and return temps and gives instantaneous kW heat rate and the accumulated kWh. This seems to be most accurate way I could think of and heat losses are included in the total. Divide gas consumption by energy meter read over the period and multiply by 100. Ideally this will be over a period where no DHW is being used, as I have the UFH on 24/7 as a single zone, overnight is best. Or do it over a few days and take my typical 5kWh off for DHW. On a really cold day and low DHW day, even without adjusting for DHW the energy meter is reading the same or lower than gas consumption.

There are three different devices. Volumiser goes in either the supply or return piping, it just adds volume. It is a simple in/out devise, it does not provide any hydraulic sepereration. Buffer as above by @PhilT. Can be 2, 3 or 4 port, but separates the primary and secondary circuits, and is connected to both the flow and return circuits. Simpler to a LLH but with additional volume.

Very true, with a large HP, but in the context of a small exhaust air HP, the OP was discussing, which should only draw 100s of W, maybe not.

People will often tell you a buffer or volumiser kills efficiency, if well insulated and operated without a thermostat that is not the case. Long run times is what give you efficiency and doing so at the lowest temperature to give you a comfortable temperature. A buffer is only inefficient when you are charging it to a higher temperature than you need on a fixed thermostat. As an example, I am using a 180L buffer, connected to a gas boiler and UFH. Have added loads of additional insulation to the buffer, buffer floats on boiler supply temperature (no thermostat). Boiler return flow temps don't go a over about 30 unless below -5, but with a min turndown of 6.7kW I get a decent runtime (even with an average 0.5kW demand). Efficiency of gas to heat conversion (gas meter to heat heater at the UFH) is +/- a little sitting at 105%, due full condensing all the time. Running the buffer at 34 on a thermostat gave around 95% efficiency. Even though run time was long, boiler return temps were higher. All the above is true for any heat source.

Or just get a suitable size for hot water and fan coils, you have to run ducts for a ducted system, so just as easy to run pipes.

Grant do an external volumiser that goes behind the heat pump. They also do a compact internal buffer/volumiser also. grant-combined-volumiser-low-loss-header-installer-uk-doc-0184-rev-1-0-november-2022 (1).pdfgrant-external-volumiser-installer-uk-doc-0183-rev-1-0-november-2022.pdf

Exhaust air heat pumps, i.e. those attached to a tank for heating DHW, seem to do a good job, get best CoP from taking internal air instead of external air. Some are coated tanks with require an anode changed annually 😥 but can cost the same a duplex stainless cylinders. A normal UVC and a smallish fixed duty heat pump would possibly give better reheat times. If your not careful you will have a house covered in external heat pumps. Any sort of heat pump is better use of PV than resistance heating as the CoP will always be better.

Should be easy, until you add in ventilation heat loss, which is a big variable. Does the sun poke its head out and give some solar gain...

Just takes a lot longer as floor response time is slower. So basically set everything as per loop lengths and adjust from there.

Want to get some things finished off outside, but weather here not playing, too cold

Trouble with the small area on their own zone, is what happens when they are the only zones opens - your number of litres engaged with the heat pump plummet and you get short cycling. Your better keeping as a single zone and balance the loops to get the correct heat in the rooms. Upping loop flow rate increases heat output of the loop, decreasing, decreases output.

Not completely - it's delta T. Just double checked, 58L at DT 5 gives 10 min run time, with output of 2.5kW and 0.5kW demand. Off time should be around 45 mins. With same DT and 1kW demand only need 45L Run time is dependant on DT Volume Heat output Heat demand.

Depends on direction, if tilted, if flat that's ok for summer, but winter out will be next to zero.

Think I worked out that a 2.5kW output and only 0.5kW heat demand, neef a heating system with a capacity of 45L, this needs to be always open to the heat pump, then your run time will be over 10mins. Which is therefore not shirt cycling. If you have loads of small zones that could shut off, you would need a buffer to meet or exceed the 45L.

Sound like you need a ventilation strategy, before you start making improvements other your house will start to turn black and your CO2 levels raise, all which will make an unhealthy home.

No the sarking boards have a gap, and the slates have a natural gap also. It's not normal to batten below natural slate in Scotland, but we have to install sarking boards.

If your flow through the loops is steady and the pump is a consistent steady noise (not noisy), then there is unlikely to be air in the system. You will hear air movement going through pump, if a blocked slug of air you get no water flow through that loop.

Mine gathers no data, I have to do it manually. That was me last year, on/off thermostats, a buffer not fully engaged, boiler run times too short. But all that's important is gas used, v heat input into the floor (I now a use a heat meter). House temperature being comfortable, that's a given. Monitoring return temp is really useful as it has a direct correlation to boiler efficiency, when coupled to boiler run time. Was charging my buffer, using a thermostat to 34 degrees, the boiler return temp would slowly ramp up settle out at 40, with a flow temp of around 60. System efficiency was around 94% (about 40% better than last year). Taking the thermostat off and leaving the buffer to float without a thermostat and running on WC, the return temp now almost never goes above 30. Boiler run time is about 12 to 14 + mins, efficiency now is around 105%. Not as good as a heat pump, but good for a gas boiler. Looking at the flue, you cannot tell the boiler is running even on a cold day.

We spray foamed ours. We block house moisture from getting into the roof structure and if it does the foam is open cell, the roof outer membrane is vapour open so any moisture can escape. Roof construction is Slates. Breather membrane. Sarking boards 254mm posi rafter. 100mm underdrawn with counter battens. Full fill spray foam - 354mm Airtight, vapour block membrane 50mm counter battens Plasterboard. Problem with spray foam reports is people putting it, where it is not appropriate.

If your UFH is being supplied via a thermal store, this will only have a header tank either built in or an insulated one above it. So your UFH is an open vented system, not a pressurised system. That is pretty much how ours is, and the UFH gauges register 0.2 bar pressure. Your gauges are showing how much pressure the pump is having to develop to pump water around. As the heating demand is switched off the drop is just pressure depleting to show the system head from thermal store header tank. 10m of head is 1 bar pressure on the gauge. If your UFH is taking it's feed from the thermal store, your pumps may need to be turned down. Keep reducing its speed until you see a change on the flow gauges, then take up to next speed.

I've played with many options. My system is heat pump ready, but on a gas boiler. Started last year with every room as a zone, a buffer that wasn't correctly plumbed, lots of short cycling. Slowly refined it, testing gas usage, flow temperature and comparing against a heat meter. Have tried batch heating, at high flow temps, fixed medium flow temp controlling heating on thermostats, and weather compensation. Some finding If you have some zones on and others off, in my house the flow temp is generally 2 degrees hotter, for the same overall house temp. I have run the buffer on a thermostat and the UFH on a fixed flow temp, gas to heat efficiency 95%. Also found that cheaper Reliance mixer isn't as good as an Ivar one. The benefit of the Ivar is the ability to adjust internal recycling proportion, so fine tuning is better. Basically now set up on full weather compensation, through Ivar mixer. All room thermostats moved to about 21 degrees (out of the way). Set flow temp to give main room 19 degrees and bedrooms 17/18 (Adjusted flow rate). Compensation curve varies between 25 at 10 degrees outside to 32 degs at -9 deg outside. Gas to heat efficiency now running at 102%. Have now added a nighttime setback of 2 degs for 7 hours to see how that goes. Currently I do not need the thermostats, they are just there to save decorating.

Plus you have an anode to replace 😥

Think you may be disappointed looked at the user manual and it says with 5kW the reheat time is over 3hrs. Which may be down to the small surface area of the coil.

If your heat pump modulates down to 2.5kW and your system volume that remains always open to the heat pump is above 45L then you will have a run time over 10 mins with a load of only 0.5kW. so you are not short cycling.