MortarThePoint

@JohnMo to confirm the strategy: - control heat flow by varying flow temperature (called Weather Compensation), colder outside means more heat lose so higher flow temp. - use manual manifold flow valves to set relative flows into each room - ASHP runs constantly (when outside temperature is below some threshold?) - no room thermostats needed - no manifold actuators or controllers needed

I haven't installed yet. Bought a reel of 22mm before learning/deciding 15mm will be OK. Might be able to use to service the garage with cold water.

I'm feeding most of my basins with 10mm direct from the plant room. 5l/min feels fine (a pint in 7 seconds) and mixed with cold the flow would be greater , e.g. 10l/min if 50/50. The numbers suggest 15mm @ 10m gives bags of flow for a shower. For a bath, dead volume isn't really relevant as you run all the water before using it. For 10m, 15mm has a dead volume of 1.1 litres (7sec at 10l/m shower) whereas 22mm has a dead volume of 2.5 litres (15sec at 10l/m shower). Bath filling time is then the only other time based factor. As @Nickfromwales says most taps have a limited flow rate. I don't know what taps you are thinking of using, but I find it difficult to get data. "A flow rate between 10 and 15 litres per minute is considered acceptable but can be improved. A flow rate that is above 15 litres per minute will be regarded as good." [Plumbworld] 15mm pipe drops around 1bar with a flow rate of 15 litres/min over 10m with a couple of bends so that should be fine. I like to run the numbers to understand it, but put much more sway in what people like @Nickfromwales have learnt to work.

I've forgotten all the corners in the UFH pipe which will up the pressure in the loop itself, but pressure dropped there should still be low. Is that at the moment or when running full wack? 0.14bar and 12W suggests a flow rate of about 40 l/min. I'm guessing you temperature drop is under 5C. I've seen UFH checklist type websites that suggest pressure should be 1 - 2 bar but maybe they're wrong.

Makes sense. I am planning to use the Wunda auto-balancing actuators. They look to maintain a 7C temperature difference when actuated so should make my life easy. The loop itself doesn't seem to drop much pressure if you have a low system flow temperature, like 35C or 40C. The heat comes out relatively slowly so the flow rate has to be quite low (e.g. 1.1l/m for a 8m2 area supplying 400W of heat). It feels like the flow gauge (or auto-balance actuator) is dropping most of the pressure in a low temperature system. I think you'd normally need to cope with the varying number of loops switched in and their relative resistances as you said. If using the auto-balancing actuators, it should be possible to have a low Flow pressure, well under a bar. The actuator could adjust to compensate for another loop switching in and out. Even if the manifold is a 50m round trip away, 28mm pipe should work with only 0.5bar (11.2kW makes for 32l/min flow which has a pressure drop of 244mbar over 50m of 28mm pipe). I am thinking in part about the pump power consumption which if an 11.2kW ASHP system and running at a flow pressure of 1.6bar would be around 100W. That could be as much as 5% of the electrical energy (as the 11.2kW is the heat not the electricity which could be 2.2kW if COP is 5).

Am I right in thinking the flow gauges act as a restriction to set a flow rate based on the inlet (aka Flow) pressure? Does that mean the majority of the pressure drop is across that restriction. If there is 0.4kW of heat coming from a 100m loop of UFH pipe, then with a dT of 5C the flow would be 1.1 l/min and pressure drop will be around 21mbar, so tiny.

I'm interested to know what typical flow and return pressures are in an UFH setup? Not temperatures, but pressures. Here are some useful bits of info: Required peak flow rate, Qmax_litres_per_minute = (60 * ASHP_Power_kW) / (4.2 * Termperature_Drop_C) e.g. (60 * 11.2kW) / (4.2 * 5C) = 32 l/min UFH power Watts/m2 = (3.34*(FT - RT) - 14.78) * 0.82^((pipe_centres_mm - 100) / 100) e.g. Flow temperature of FT=40C, Room temperature of RT=18C -> (3.34*(40-18) - 14.78) * (0.82^0) = 58.7 W/m2 [derived from 1] Pump hydraulic power in Watts = (Q_litres_per_minute / 0.6) * (Flow_Pressure_bar - Return_Pressure_bar) e.g. (32 l/min / 0.6) / (2bar - 1bar) = 53W (random pressures)

With an Heat Transfer Coefficient of HTC=372W/K, ignoring any gains, means 10% duty cycle per degree of difference between indoor and outdoor with 11.2kW Ecodan 11.2kW on min setting (4kW). E.g. duty=60% when 12C outside (2.4kW average), 100% when 8C outside (4kW). Gains work out as something like 4C equivalent, shifting those temperatures down to 8C and 4C respectively. That could allow lower flow temp and better COP. Perhaps FT=30C giving a COP of 5 when 7C outside. lots of scope for optimising.

Are Ecodans binary in power delivery? Full on or full off or can you get an 11.2kW to deliver 6kW of power? I presume the COP would be worse, but is there data on that?

I've installed UFH upstairs and downstairs so should be able to dissipate 11.2kW with a flow temp of 35C or a bit above. Is short cycling when it turns on for a short duration? I imagine that is influenced by the allowed temperature swings on the thermostats. Is that correct? If so the cycle on time would be the same if I allow proportionately larger temperature drops. All my options are the same size I think. Vary between brands though.

The hour figures are simply outputs that show how long the ASHP needs to be on for at 100% to provide the required energy. It could be run at a lower setting for longer if that is desirable. I have done a basic thermal time constant model that suggests the house will cool down (i.e. loose heat unheated) at a rate of 0.1C/h when it is 4.2C outside (so dT = 14.4C). The cooling rate is 0.07/h or the time constant is 144h (6days) (half life 4.2days). With 11.2kW I'd almost be able to only run the ASHP during E7 electricity and only suffer 1.4C temperature changes. I know the COP would be worse as colder at night, but the electricity is cheaper. I don't fancy making a 60kWh battery at the moment to allow the electrical demand to be spread across the day. I know this already from the SAP: Total Fabric Heat Loss 234 W/K (A) Ventilation heat loss (max): 138 W/K (B) Heat transfer coefficient (max): 372 W/K (A+B) If AT=4.2C and indoor is 18.16C then average power requirement is 372W/K * (18.16C - 4.2C) = 5.19kW if there were no solar/metabolic/appliance/etc gains. In December the solar gains seem to average 0.47kW and the internal gains are about 1kW. 5.19kW - 1.43kW = 3.76kW SAP has a monthly space heating demand for December of 2774kWh: 2774kWh / (24h/day * 31days) = 3.73kW Water heating is shown in the SAP as 220kWh/mo so that averages to: 220kWh / (24h/day * 31days) = 0.3kW. In theory I could have a smaller ASHP, but I would want extra grunt for when it is unusually cold. 8KW would suffice (down to AT = -11C). Other than capital cost, what is the main downside of having too big a unit? Do you mean Jeremy's Spreadsheet?

Dimensional comparison:

I think I'm more drawn towards the Ecodan due to its proven track record. If I needed 14kW it would be a different matter. My SAP shows a peak monthly heat demand of around 2700kWh in December with an average outside temp of 4.2C. that works out as about 90kWh/day so about 8 hours of 11.2kW (3.75kW average). That's with an indoor to outdoor dT=18.6-4.2=14.4C. If outside goes to -5C then dT=23.6C and that would make for 90*(23.6/14.4)=150kWh/day so about 13hours of 11.2kW (6.1kW average). There would be an additional hot water demand but pretty low (max. 300kg * 50C * 1Wh/kgC = 15kWh so about 1 - 2 hours worst case). Bear in mind that would have to be a day with average temp of -5C which where I live is unlikely.

The 11.2kW/12kW units are very similar in quietness (47 vs 46), but the Samsung 14kW units are a fair bit quieter than the Ecodan units.

Samsung have come out with an interesting looking new ASHP, EHS Mono HT Quiet, R32, Heat Pump, 12.0kW. Also available 8kW and 14kW. Available single and 3-phase. Unlike with Ecodan/Zubadan the 14kW unit is the more standard 1m height which could be a big win for people who need a little extra power. Prices look similar. Black in colour. They have a headline COP figure, but then give power out and power in data at varying FT and AT: On first inspection the COP looks worse, as at most ambient temperatures the resulting values are lower. However, at the key temperatures in the South of England, they have done a better job of optimising the design and get better numbers (suspicious?). Red is the better: 14kW model has similar COP numbers in the 2C to 12C range (1% worse than the 12kW model): The basic linear model makes for average COP values of 4.41 at FT=35C, 4.05 at FT=40C and 3.68 at FT=45C. That's about 2.4% better than the Ecodan figures, but the linear model doesn't fairly represent the improved better optimisation of the Samsung (e.g. 9% better COP at AT=7C). The Ecodans have been around for longer, so perhaps there are some optimisations not reflected in their data. There's more in field experience for the Ecodan which is a plus.

The soppy can works fine. Looks like I have a load of duff cans

A reasonable formula for the COP of the Ecodan 11.2kW is COP=(0.521 - 0.0068E*FT)*AT + (4.44 - 0.0485*FT) where AT is the ambient temperature and FT is the flow temperature, both in C. Using that I get my expected average COP based on the flow temperature with the assumption that the flow temperature stays constant throughout the heating season: COP = 7.47 - 0.088*FT That assumption feels reasonable given most of the demand is across 3 months with an ambient temperature within 1C (DEC-FEB) and the rest is mostly still within an ambient range of 2.8C (NOV - MAR).

I have found a databook from Mitsubishi Ecodan and here is some performance data for their 11.2kW unit: https://library.mitsubishielectric.co.uk/pdf/book/ATW_Databook_R32_2020#page-60-61 Based on my SAP and that data (nominal), I should achieve (my model) an average COP of 4.34 with a flow temp of 35C or 3.45 with a flow temp of 45C. Having put in UFH upstairs as well as downstairs, I will hopefully be able to use the lower flow temperature (UFH power output W/m2 data below). This all ignores domestic hot water, but I'm OK with working out the space heating needs as a priority. Modelling as linear above 2C ambient would have been fine. Here's UFH heat output vs flow temperature: data from link below except red which is from a good linear fit. https://www.tradingdepot.co.uk/info/plumbing/polypipe/underfloor-heating-heat-output-tables/

It was in the house we're currently living in so temperatures were OK. I'd be surprised if it went above 25C

Temperature range was fine, but they were on their side as packed by supplier. All dated mid to end next year. Arrived in May this year (5 months ago)

I have 6 and have given each one a shake. Two make a lot of slopping sound where as the rest bearly make a sound. I'll try a sloppy one.

Do new cannisters of FM330 normally make a slopping sound when shaken. These don't but I presume that's because they are completely full. I did manage to get a trickle of FM330 out of the older gun.

One gun is brand new. Both sprayed cleaner ok. Yes, unscrewed until it fell out.

I've bought some of this and am unable to spray it with my normal foam guns. One is an Everbuild P65 and the other is a no-name Amazon foam gun. Do you need a special gun (e.g. from Illbruck) or do I have a duff batch of foam (still well in date code).

I suspect I have over done things a bit, but it should be OK. I pushed the Isokern adapter onto the pumice and it seemed firmly attached by the rope friction. I made sure it was level in both directions. I then added a support either side of the adapter that barely (if at all) touches it but would stop it dropping down. This support proved useful for two other purposes. I hung the cut to length vitreous pipe from the support as I slid the stove in and having then lowered the pipe into the stove, cemented it in place. I've been concerned about the steel lintels getting hot, so I then wrapped the pipe with fire blanket (25mm) and put some additional A rated APR insulation in there to keep the heat away from the lintels. The supports helped constrain the bio soluble fire blanket. A makeshift 'register plate' made as two halves out of 3mm aluminium finished it off.