Did the plumbers flush all the pipework prior to filling the system? I wonder if there is some foreign body in the downstairs pipework that is limiting the flowrate.
Not sure. And I suspect not. We moved in ahead of completion, as project was running late. They installed the downstairs rads (Eskimo), then the towel rad in WC at an ever later date. Not 100% sure they flushed it at that point.
I just tried to do some recordings but got interrupted twice already in 25 mins. 5 min intervals seems realistic my end. I'll try and see today if get an hour and hit the start of a cycle and am not interrupted to record. Failed attempt below just incase of any use:
Before carrying out the testing I would suggest checking the calibration of all the sensors. Mounting the sensors on the pipework as suggested.
Sorry I did not make myself clear. The correction factor for the Eskimo radiators is different from that normally applied to estimate the thermal energy output. This would seem to indicate that the Eskimo radiators emit more thermal energy than a similarly sized standard radiator. Is this actually correct?
Before carrying out the testing I would suggest checking the calibration of all the sensors. Mounting the sensors on the pipework as suggested.
Sorry I did not make myself clear. The correction factor for the Eskimo radiators is different from that normally applied to estimate the thermal energy output. This would seem to indicate that the Eskimo radiators emit more thermal energy than a similarly sized standard radiator. Is this actually correct?
Thanks Derek, I'll look at calibration before next tests.
Yes the Eskimo seem to stick with having a better thermal output, I seem to recall on some googling that someone had queried this with them and they stuck with it, hence their correction factors being more favourable.
Looking at the difference of Bed 1 v Living 2, using the same correction factor applied to the Eskimos, it would look like this:
Bed 2
19.8 (floor area) x 2.44 (ceiling height) = 48sqm
2x 1000x500 Stelrad Compact with Style K1s
746 per rad at D50
0.301 D20 correction factor
449W (by multiplying rad output x 0.301)
Living 2
28 x 2.59 = 72sqm (50% larger volume than Bed 2)
1x 963x200 Eskimo column = 880W at D50
1x 1694x200 Eskimo column = 1540W at D50
0.301 D20 correction factor - this is Stelrad's not Eskimos 0.41 at D20
728W (60% larger than Bed 2)
This is where I'm struggling to understand how the upstairs performs so much better than downstairs, as on paper wouldn't expect the difference to be so great. Also using the delta 16.5 rating, would expect Bed 2 to underperform but doesn't seem to at all. In fact it feels like upstairs is very oversized as hard to run it at an expected LWT without rooms getting too hot
Fail 3 times for me to read as interrupted. Then hoped to get the min 40 reading but ASHP had switched off.
Can see though that rad 1 started to get closer temp TRV side as rad 2 towards the end of the cycle.
Rather than rush the process and get limited results I would suggest that you wait until you have time to check the calibration of the sensors and install them as suggested. The weekend may be a better time.
I would also suggest that you continue taking the readings after the heat pump stops running since this will indicate the rate at which the various sections of your system cool down.
To obtain readings at 1 minute intervals you could forego the LWT and RWT measurements if necessary.
Fail 3 times for me to read as interrupted. Then hoped to get the min 40 reading but ASHP had switched off.
Can see though that rad 1 started to get closer temp TRV side as rad 2 towards the end of the cycle.
Rather than rush the process and get limited results I would suggest that you wait until you have time to check the calibration of the sensors and install them as suggested. The weekend may be a better time.
I would also suggest that you continue taking the readings after the heat pump stops running since this will indicate the rate at which the various sections of your system cool down.
To obtain readings at 1 minute intervals you could forego the LWT and RWT measurements if necessary.
Thanks Derek, would it be worth measuring Bed 1 (above Living 2) as well once this is all setup.
And also potentially the reported room temps as well?
Please provide whatever data that you can obtain. In situations like this it is much better to discard unwanted data than have to repeat a test because something was missed.
I was going to suggest measuring the floor temperatures both upstairs and down to try to ascertain the source of the thermal energy heating the bedrooms, since it must be coming from somewhere. Do you get much solar gain?
Please provide whatever data that you can obtain. In situations like this it is much better to discard unwanted data than have to repeat a test because something was missed.
I was going to suggest measuring the floor temperatures both upstairs and down to try to ascertain the source of the thermal energy heating the bedrooms, since it must be coming from somewhere. Do you get much solar gain?
The front of the house is pretty south facing, so those rooms (Living 1, 2, Bed 1 and 2) tend to get solar gain. However the 2 poor performing rooms are part of that.
Now floor temps is interesting, as all the carpeted rooms (upstairs, the stairs themselves and living 2) have 16mm carpet with 9mm thermal underlay. Whereas the downstairs hall and living 1 have engineered 25mm wood flooring with no thermal underlay, straight onto the concrete floor, so could be getting a greater thermal hit.
In an effort to summarise observations so far from everyone, I'm trying to keep a list to go back to the builder/architect with at some point.
Pipe sizing:
It appears 22mm plastic piping was used where 28mm would have been appropriate - this increases head loss versus 22mm copper pipes
Findings with temp probes (probes to be checked per Derek's instructions):
Seeing 1C drop within plant room from LWT top right of LLH to heating zones (e.g. 34C LWT - to 33C to zones)
Seeing a further drop of 2C to TRV side of rads in heating zones (e.g 34C LWT - 33C to zones - 31C at TRVs)
Cycling issues:
With upstairs zone relying on TRVs/heatmiser panel - this would appear to cause greater cycling than using lock shields and maintaining the zone on (the heat dump mainly occurring in bathrooms - which is a useful heat anyway). However due to the LWT perhaps being too high for upstairs, it appears upstairs zones start to get too hot even with lock shields almost closed completely. Today tested Bed 1 with one completely shut, and 1 almost completely shut and that still hit 20C (effectively 1 rad off, 1 barely getting flow - both fully on, the room goes above 21C)
Plant room elements:
Zone valves for the 3 zones aren't ASHP flow rate appropriate - though downstairs is rated higher than others (why was a different one used?)
Instead of 3 valves for the zones and 1 for the DHW/CH valve - a single large bore 3 way valve diverting between CH and DHW would be more appropriate (keep zones on, but balanced to avoid overheating)
The LLH - could that be replaced with a volumizer (note aside from the probes not being checked, always see with different probes that the bottom left of the LLH appears higher than the bottom right)
The bypass valve above zone valves - is that necessary - that could be taking flow away from zones with ASHP rates
Rad sizing
Delta 20 was used for rad sizing yet heat calc would indicate delta 16.5 should be used (note however upstairs still performs and over heats)
Proportionally Bed 1 v Living 2 indicates Living 2 is 50% larger, with Eskimo correction factor it's 120% more watt output, with Stelrad correction factor it's 60% more watt output - yet still under performing
something just occurred to me - if you ran a cheapo electric convector heater in your underheated room for a period, needs to be one that runs low enough, that would tell you roughly how many watts you are short. might help with the decision about the radiator sizing.
I think the issue would be everything’s been done from underneath? As ceilings were removed due to asbestos artex, it gave them that route. And in the wall runs would be murder. Coming from above is carpets etc I can’t quite recall what’s underneath - not small boards and there’s some built in wardrobes etc I can imagine it being a real pain, also the living rooms, part extend out beyond the footprint of bedrooms above due to a sloping roof, so that part would be from below I presume. I think it just wouldn’t be viable and they’d probably excuse upstairs being performant against that. Infuriating as they had full reign on this project so could have gone to town with pipe sizing.
Only heater I have unfortunately is a Dyson AM09 hot + cool fan which looks to be 2000 watts of heat power. Not sure how I could use that somehow at a lower level as I think it runs by temperature. However will suggest this as a way for them to measure the watt shortage by doing something along those lines as that’s a great way to see that, as always they look at the plant room and ASHP, not rooms themselves.
The cycling is driving me a bit mad. Today with upstairs off, some doors open the house dropped quite a bit as cycles were few and far between. With upstairs back on and coming to temp, could see downstairs benefitting, in the last hour the living room has gone from 18.8C to 19.5C with a cycle quite quickly bringing it up, but cuts short.
The other thing in back of my mind is the LLH, when it was installed wrong way round, it had a big impact. Looking back through photos of 4 probes setup since then, there is always and is now, when the ASHP is running, the bottom left (RWT from zones to LLH) has a higher temp, typically by 1C than bottom right (RWT from LLH to ASHP). When no cycle is running that equalises. I wonder if there’s mixing that just effects the LWT and RWT enough to stop the AHP running when still the Eskimo rads would be taking heat out into downstairs. Also the LWT shown on Grant panel tends to be 1-2C higher than seen on uncalibrated probes, the RWT seems to be 4-6C off panel v probes.
I’ve taken a photo of the manifold for the underfloor heating incase that shows anything awful also
This post was modified 6 months ago 3 times by Crimson
pipes - had to ask. in case it was a house with easy "just lift some floor oards" type access.
mixing - unless the flow rates are identical primary and secondary sides, then there is a guarantee of some mixing in the LLH. This is the big disadvantage of LLH. Plenty of people on this board have spent weeks trying to get balanced flow rates either side of an LLH.
cycling - (avoiding it) is all about trying to make sure all the radiator/ufh volume is engaged all of the time. which is why , the mantra is
all zones on all the time (so you don't need zone valves)
no bypass (so all flow must go through an emitter)
almost all radiators on all the time (just a handful with TRV's where you really have to)
emitters the right size for the room or close to, so by staying on all the time the room stays the right temp
balance with lockshields (and pipe sizes) so all radiators get a "fair flow rate"
the 22mm plastic pipes you have are acting like extra lockshields. As are the small bore zone valves. making the balancing act harder.
UFH pic - can't help you personally, I've never had UFH.
