Thanks again for all this. I’ve relayed it to architect and also queried things in the Calc doc as some rooms structure dates etc are wrong and a number of other factors so any size adjustments I want the calcs correct first. I’m going to tomorrow test resetting the WC with 40C at -3C. And see at what temp the upstairs requires to hit 21c. Atm they’re mostly on level one on the TRV and rooms are 18.5C but the office not sitting above 20C could be a problem or simply due to surrounding rooms temps just not being that high. Not sure how changing from a K1 to K2 would work as pipes I imagine are too close to wall.

On another note (realise I’m post blitzing but trying to comprehend as much as possible).

if currently today I’ve run the system with no weather curve at 42C. Temp has been 6-7C outside pretty constant. If the system keeps cycling and the downstairs zone is still not hitting above 19-19.5C, how does that marry up against the watt shortage? Eg the external temp is 6C external at 42C flow rate versus the design temp at 40C and -2.75C external (9.75C higher external and 2C higher flow rate). Is there a way to proportionally work that out? Eg some way of back calculating with the under sizing what flow temp is required?

Curious as I’m not seeing a pattern, eg a spot where the zone will actually hit temps as yet.

for example looking at living room 2:

200x963 = 880W at D50

200x1694 = 1540W at D50

2420W total

room requirement = 983W

delta is 16.5C (37.5MWT-21)

correction rate from Eskimo at D16 is 0.33

983W / 0.33 = 2978W requirement

2978-2420W = 558W

558W / 2978W = 19% shortfall

would you then expect to have to up flow temps by 19% to offset?

Posted by: @crimson

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On another note (realise I’m post blitzing but trying to comprehend as much as possible).

 

if currently today I’ve run the system with no weather curve at 42C. Temp has been 6-7C outside pretty constant. If the system keeps cycling and the downstairs zone is still not hitting above 19-19.5C, how does that marry up against the watt shortage? Eg the external temp is 6C external at 42C flow rate versus the design temp at 40C and -2.75C external (9.75C higher external and 2C higher flow rate). Is there a way to proportionally work that out? Eg some way of back calculating with the under sizing what flow temp is required?

 

Curious as I’m not seeing a pattern, eg a spot where the zone will actually hit temps as yet.

 

for example looking at living room 2:

200x963 = 880W at D50

200x1694 = 1540W at D50

2420W total

room requirement = 983W

delta is 16.5C (37.5MWT-21)

correction rate from Eskimo at D16 is 0.33

983W / 0.33 = 2978W requirement

2978-2420W = 558W

558W / 2978W = 19% shortfall

would you then expect to have to up flow temps by 19% to offset?

The important factor is the temperature of the water entering the radiators, which I doubt was at 42C.

The calculated heat loss for living room 2 is 983W at an OAT of -2.75C. I believe that heat loss is linear with the temperature difference between IAT and OAT, so each 1C difference would vary the heat loss by approximately 41.4W.

If the IAT is 18C and the OAT is 7C, then with a DT of 11C, the actual heat loss would be in the region of 11 x 41.4 = 455W. If the IAT is increased to 21C, again with the OAT at 7C, the DT is now 14C and the heat loss would be increased to 579W.

Assuming that the output of the present radiators is as stated above with reference to the Eskimo correction factors, then to maintain IAT at 18C would require a MWT of just under 27C, so a LWT of 28C with RWT of 26C, or a LWT of 29.5C and RWT of 24.5C. You get the picture.

To maintain an IAT of 21C would require a MWT in the region of 32C, with appropriate LWT and RWT values.

I would suggest that if you have the time you should record the following temperatures at 1 minute intervals for at least 1 hour. Ideally record LWT and RWT at the heat pump, the four temperatures at the LLH and the flow and return temperatures at the two radiators. If possible also measure the IAT and OAT and post the results for analysis.

Posted by: @derek-m

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Posted by: @crimson

↑

On another note (realise I’m post blitzing but trying to comprehend as much as possible).

 

if currently today I’ve run the system with no weather curve at 42C. Temp has been 6-7C outside pretty constant. If the system keeps cycling and the downstairs zone is still not hitting above 19-19.5C, how does that marry up against the watt shortage? Eg the external temp is 6C external at 42C flow rate versus the design temp at 40C and -2.75C external (9.75C higher external and 2C higher flow rate). Is there a way to proportionally work that out? Eg some way of back calculating with the under sizing what flow temp is required?

 

Curious as I’m not seeing a pattern, eg a spot where the zone will actually hit temps as yet.

 

for example looking at living room 2:

200x963 = 880W at D50

200x1694 = 1540W at D50

2420W total

room requirement = 983W

delta is 16.5C (37.5MWT-21)

correction rate from Eskimo at D16 is 0.33

983W / 0.33 = 2978W requirement

2978-2420W = 558W

558W / 2978W = 19% shortfall

would you then expect to have to up flow temps by 19% to offset?

The important factor is the temperature of the water entering the radiators, which I doubt was at 42C.

The calculated heat loss for living room 2 is 983W at an OAT of -2.75C. I believe that heat loss is linear with the temperature difference between IAT and OAT, so each 1C difference would vary the heat loss by approximately 41.4W.

If the IAT is 18C and the OAT is 7C, then with a DT of 11C, the actual heat loss would be in the region of 11 x 41.4 = 455W. If the IAT is increased to 21C, again with the OAT at 7C, the DT is now 14C and the heat loss would be increased to 579W.

Assuming that the output of the present radiators is as stated above with reference to the Eskimo correction factors, then to maintain IAT at 18C would require a MWT of just under 27C, so a LWT of 28C with RWT of 26C, or a LWT of 29.5C and RWT of 24.5C. You get the picture.

To maintain an IAT of 21C would require a MWT in the region of 32C, with appropriate LWT and RWT values.

I would suggest that if you have the time you should record the following temperatures at 1 minute intervals for at least 1 hour. Ideally record LWT and RWT at the heat pump, the four temperatures at the LLH and the flow and return temperatures at the two radiators. If possible also measure the IAT and OAT and post the results for analysis.

 

Thanks Derek, I’ll see if can find an hour to do this tomorrow. With the cycling it might be hard to get this however, perhaps recordings every 10 mins.

Sitting in Living 2 now. And a cycle is happening. Looks like with ASHP forced to 42C, the smaller rad gets 35.8C in, 33.5C out, the larger 33.5C in, 31.8C out. LLH top right showing 40.1C (LWT), bottom right 36.6C (RWT). According to Grant panel - 43C LWT AND 41C RWT.

Living room temp - 20.3C

Outdoor temp - 6.5C

This AM I’ve had to put the ASHP on the weather curve as it’s simply too warm upstairs with the ASHP running at 42C fixed (seems to be get 1.5V-2C lower into heating system just before zone valves). Panel showed 20.5C upstairs. I’ve no probes in bedrooms but anything above 18.5C isn’t that comfortable for us. This is with bedroom TRVs other than office one on 1/5, landing left at max.

Office is at 20.1C. Note this room with watt calcs done using a correction factor for Delta 15 has rads right sized (it’s the only bedroom that’s fully new structure so better heat loss etc), the rads in there were scaled back from K2 to K1 with others on assumption delta 20 was the correction factor (K2 would have for that room then be really oversized), but as they were sized physically to match windows seems by chance have right output. That room I’d expect then to have easily hit 21C, but suspect cycling is holding that back also.

Living room 2 was at 19.8C. Cycling seems to prevent it getting higher. Kitchen/diner at 19.3C (panel shows floor temp at 21.2C) which is however underfloor and comfortable at that temp.

I however saw that on the mail I was given with the version of heat Calc that the architect had a number of feedback points. So I’m going to ask if in fact that is the latest document. If it isn’t then not sure how I was expected to offer alternatives without correct calcs provided, irrespective of the plumbers in charge of system design then not checking every is appropriate.

All in all reflective of the project having these guys just be sloppy and cause issues.

(apologies for post blitzing yet again - posting as find things etc)

Architect responded, heat calc was last one sent over however architect pointed out queries were outstanding and things such as ceiling heights were wrong etc and it was a battle to try and get updates.  Hence we had the whole scenario of me coming with options as rads they came with didn't physically fit in spaces.

Builder is pushing back tomorrow's meeting as wants calcs looked at and plumbers to confirm with Eskimo the ratings expected from these rads with flow temps.  Has also suggested once we all re-gather that the heat specialist also attend.

I've now put a probe in the main bathroom to see what temp that sits at.

According to a delta 15 calc (can't find a correction factor for delta 16), Watt requirement would be:

• 509/0.21 = 2423W

Rads in there are:

• Reina Florina 1235x500 = 781W
• Corex Vertical 1800x500 = 1058W
• That's 584W (25% approx) short of requirement

That room has never felt cold and sitting at 20.8C but obviously ASHP ran hot last night.

So in my head I don't know how accurate calcs are, not that I'm hoping to avoid rad changes, I just don't know what anything should be if that makes sense.  And I think builder and plumber need to take a step back and look at things overall rather than just attempt fixes with buffer tanks/volumisers.  If things aren't sized correctly/balanced, it's going to be hard to run this properly.  Seemingly the builder seems on board with this also.

Currently ASHP is at 37C LWT, 35C going into heating zones, 9C OAT.

There's a bit of solar gain today, living room 2 (south facing) sitting at 19C even with the ASHP dropped down. Bedroom across from my office is 20.7C, rising quickly now TRVs opened to max, that room would effectively be 25% lower watt output if Delta 15 assumed (as downsize from K2 to K1 was on presumption of Delta 20 not 15)

I wonder if now I'm pulling more heat out upstairs opening up bedroom TRVs if I'll see the ASHP cycle longer, and thus the living rooms pull temps up higher.

After today my plan is to see if putting the ASHP in 40C max (the design spec), how these rooms fair.  On Grant's other default settings that puts LWT at 35.65C at OAT 7C , or 34.8C at OAT 9C (which it now is today).

I'm impatient, bedrooms and office hit 21C, so I've now changed to 40C max over 45C max.  Living room was 19.8C .  Have noticed ASHP is cycling longer with upstairs taking heat out.  Note the other half informed me that she had opened our sliders in kitchen/diner with hallway door open, and downstairs zone had dropped to 18.5C earlier, so could explain why in this instance downstairs is catching up (not helpful when trying to monitor temps lol!)

@crimson have you tried (with all zones and all trv's open) pinching the lockshields down somewhat on the rooms that do heat up well, so as to force more water flow to prefer going to the room that does not heat up so well? If you already tried this, and with a forced higher flow rate it still doesn't heat up, then that does point the fingers at the radiators in the under-heated room being undersized (for the WT you are running at). If you didn't then try it (or get your plumber / heating engineer to) - its an exercise in trying to balance the flow rates in all your rooms against the heat loss and radiator capacity.

Also make sure you've checked for "shortcut" radiators. i.e. one that lets water through really easily. Ladder towel rails can be a common culprit. closing the lockshield partly down is again the answer.

the water temps you are trying to run at 35C ish for 7C outside, is a good and appropriate target for radiators. thats what my system runs at.

a buffer tank will not fix this.

Posted by: @iancalderbank

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@crimson have you tried (with all zones and all trv's open) pinching the lockshields down somewhat on the rooms that do heat up well, so as to force more water flow to prefer going to the room that does not heat up so well? If you already tried this, and with a forced higher flow rate it still doesn't heat up, then that does point the fingers at the radiators in the under-heated room being undersized (for the WT you are running at). If you didn't then try it (or get your plumber / heating engineer to) - its an exercise in trying to balance the flow rates in all your rooms against the heat loss and radiator capacity.

Also make sure you've checked for "shortcut" radiators. i.e. one that lets water through really easily. Ladder towel rails can be a common culprit. closing the lockshield partly down is again the answer.

the water temps you are trying to run at 35C ish for 7C outside, is a good and appropriate target for radiators. thats what my system runs at.

a buffer tank will not fix this.

Thanks @iancalderbank, I can give that a go, perhaps all upstairs rooms bar my office as a first attempt.  Just a note - if TRVs were all down to 1/2 is that effectively doing the same thing?

@crimson I’m not Ian, but, not really! The lockshield is a restriction to flow which is set and remains constant. A TRV provides dynamic changes with changes in temperature. The TRV is most likely to cause you greater variations in flow and thus unpredictability - quite the opposite of what you are aiming at. The lockshield setting (along with all the other lockshield valves would be used to balance your system in a steady state way. Once (and whenever this might be!) the system is settled down leaving all the TRV’s fully open, you may then wish to use the TRV’s as limiters to prevent severe overheating (such as when there may be solar gain in a particular room). The usual advice is to set the TRV’s 1-2 degrees C. Above your desired temperature thus, under normal circumstances, the valves will be fully open and not affecting the overall dissipation of energy from the flow pipe. Regards, Toodles.

Posted by: @toodles

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@crimson I’m not Ian, but, not really! The lockshield is a restriction to flow which is set and remains constant. A TRV provides dynamic changes with changes in temperature. The TRV is most likely to cause you greater variations in flow and thus unpredictability - quite the opposite of what you are aiming at. The lockshield setting (along with all the other lockshield valves would be used to balance your system in a steady state way. Once (and whenever this might be!) the system is settled down leaving all the TRV’s fully open, you may then wish to use the TRV’s as limiters to prevent severe overheating (such as when there may be solar gain in a particular room). The usual advise is to set the TRV’s 1-2 degrees C. Above your desired temperature thus, under normal circumstances, the valves will be fully open and not affecting the overall dissipation of energy from the flow pipe. Regards, Toodles.

Thanks Toodles!

I'll sort this now, as I can see my office temp is climbing (currently 21.3C) and suspect that's because the upper floor is warming up with the TRVs now at max.

@crimson basically - exactly what toodles said!

set all TRV's to max (or better, take them off) whilst doing lockshield balancing. The lockshield setting sets the maximum flow rate that can go through the radiator. because its a fiddly little valve, often all the meaningful adjustment is in the first full turn from open, or less. This can be a very time consuming process.

Whereas a TRV gradually shuts a radiator off as a room warms up. thats what heacol was referring to about dynamic balancing. you can't balance a system thats got changing parameters.

in a perfect world heat pump system, you don't have TRV's anywhere because the "radiator flow rate times radiator size times water temp"  (all multiplied by the appropriate coefficients of course) equals the heat needed in that room. In that equation you've got 3 variables to play with. One requires physical change to vary (new radiator), one you don't want to (water temp) as it costs you more. So you try to tune flow rate.

In a less than perfect world: TRV's only in rooms that you want to keep deliberately cool, have high solar gain or another heat source.

by restricting the flow rate to the "too hot" radiators, you are trying to force the water flow to try to find other paths. which will (hopefully) be via your "too cold" radiators. If there are other constraints in the system though (like valves or pipes that are smaller than is ideal, or pipe runs that are too long) this can be difficult, you might be trying to redirect it somewhere that it doesn't want to go...

• @iancalderbank In my own case, I started from the coolest room with that Lockshield valve fully open, then progressed around the house from the warmest room reducing the valves ‘openess’ until I had approximately the same temperatures in all rooms. Through a number of rounds, I gradually refined the settings and as Ian mentioned, some valves are on the last turn from being fully shut; one of mine is no more than one eighth of a turn from completely closed - great fun can be had establishing these final settings! I have one Hive programmable TRV on our bedroom rad enabling me to lower the overnight temperature. I used the Hive TRV’s on the old gas powered heating system so felt I might as well utilise one for this purpose. Regards, Toodles.