New learning.

Concept of a heat dump is a good one to get longer cycles and side benefit of heat from towel rads upstairs throughout the day. However having a zone valve manually open means the hot water cycle heats that zone at 50C lol.

Only noticed as had some probes in a bedroom on a rad trying to adjust the lock shield today. And after the other half pointed out the bath wasn’t very warm I ran a boost cycle (never do this). Just randomly walked past the room and could feel the heat.

I guess the TRVs turned down before today probably mitigated this but I’ve obviously for 3 weeks had the landing rad and towel rads getting extra nice and toasty with the hot water cycle.

Anyway fix has been to re-enable that zones panel and set the valve to auto but set the zone temp higher than it will hit.

Other learning has been the lockshields I probably need to go opposite. Close completely then slowly open slightly every now and then until rooms get to temp upstairs that are desired as what I thought was a number of turns obviously wasn’t as the rad was nice and hot.

Living room 2 still sitting at 19.5C but after today’s having to run a boost and the family having a large portion of the ground floor open to outside I can’t really tell if seeing a performance hit running at 40c max this afternoon.

Tomorrow I’ll restart looking at upstairs using lockshields over TRVs to control room temps and see if with that the downstairs zone pulls up due to less cycling and more balance for downstairs. Also will keep an eye on my office being at 21C with TRVs and lockshields maxed out. Today I started playing with one lockshield as the temp crept above 21C but again would have been form the 3pm-4pm cycle and me just not noticing at that time the temps on the rad.

now meeting with plumber and builder is pushed back I’ll keep experimenting to see what I can get on a 40C max cycle using a default weather curve (other than bottom end -3C instead of -4C and top 40 instead of 45C giving a LWT around 35C at 7C OAT).

@crimson

I'm afraid that you are likely to be 'chasing your tail' if you have zone valves opening and closing under different conditions. When heating DHW the feed from the heat pump should only go to the hot water cylinder, when in central heating mode all relevant zone valves should be open together. It is only then that you will stand any chance of balancing the flowrates in the primary and secondary circuits. Since you still have the plumbers involved it may be better to convert the LLH into a small volumiser as detailed previously.

Once you have more balanced flowrates then open all the TRV's and lockshield valves and allow the room temperatures to stabilise, though you may have to lower the WC curve if it gets too warm. Identify the coldest room and leave all the valves fully open there. Starting at the warmest room bring down the temperature using the lockshield valves, though allow sufficient time for temperatures to stabilise between adjustments. Once you have the desired temperature in the warmest room then do the same in the next warmest, and so on and so forth until all rooms have been done. Then repeat the process since there will probably have been interaction between rooms. This is a long slow process that could possibly take weeks.

Because you also have UFH you will need to adjust the flow setting valves for each UFH loop.

Once all the heat emitters have been correctly balanced then raising or lowering the LWT should have a balanced effect throughout your home. Obviously there may be some rooms that suffer solar gain which is where a TRV may be needed to limit the temperature rise.

Posted by: @derek-m

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@crimson

I'm afraid that you are likely to be 'chasing your tail' if you have zone valves opening and closing under different conditions. When heating DHW the feed from the heat pump should only go to the hot water cylinder, when in central heating mode all relevant zone valves should be open together. It is only then that you will stand any chance of balancing the flowrates in the primary and secondary circuits. Since you still have the plumbers involved it may be better to convert the LLH into a small volumiser as detailed previously.

Once you have more balanced flowrates then open all the TRV's and lockshield valves and allow the room temperatures to stabilise, though you may have to lower the WC curve if it gets too warm. Identify the coldest room and leave all the valves fully open there. Starting at the warmest room bring down the temperature using the lockshield valves, though allow sufficient time for temperatures to stabilise between adjustments. Once you have the desired temperature in the warmest room then do the same in the next warmest, and so on and so forth until all rooms have been done. Then repeat the process since there will probably have been interaction between rooms. This is a long slow process that could possibly take weeks.

Because you also have UFH you will need to adjust the flow setting valves for each UFH loop.

Once all the heat emitters have been correctly balanced then raising or lowering the LWT should have a balanced effect throughout your home. Obviously there may be some rooms that suffer solar gain which is where a TRV may be needed to limit the temperature rise.

thanks Derek. I’ll try and push for the LLH to volumiser as well as simplification of zones. The DHW cycle heating upstairs was an oversight of the heat specialist not thinking of that it seems. Or he forgot to ask me to turn the panel back on but adjust the temp so it never turns off (unless it’s DHW).

Tonight downstairs is slowly getting up, 19.8C atm. Suspect this is as instead of TRVs upstairs it’s now more rads taking out heat so the cycles are longer, with some lockshields turned down but not yet significantly enough to keep the temp capped at 18.5-19C for bedrooms and leaving office around 20.5-21C.

I’m basically rushing atm to see if downstairs can hit temps at expected LWTs against OATs to ensure it’s not a calc issue/Eskimo rad issue. But when the zone is isolated on its own it doesn’t seem to create enough of a delta for the ASHP to stop cycling off. From what the heat specialist said this is as it’s such a small zone volume wise and the rads appear to work at a low delta, still increasing heat but the ASHP cycles off regardless it’s end. Probably the LLH doesn’t help with that. He felt physically alone that was rather small.

The UFR zone could use adjusting loops like you say as that closes off often.

I’ll see overnight how this goes then commence the balancing from lockshields upstairs.

I'm pretty much up against it as contract wise they obviously want to close this up. Plumbers feel they’ve installed to spec and their approach doesn’t seem flexible. I guess my only hope is get what I can done from them, then look at a third party to adjust the system. Be it we just get the Eskimos doubled in size via them. Then afterwards at my own cost look at zone simplification and LLH swap out.

I think it’s safe to say the rads downstairs appear to be the issue.

Keeping upstairs on but reducing lock shields down does seem to have reduced cycles.

As temps got to low end of 19C in downstairs with this and ASHP was 40C max that to me shows cycling was very much an issue when only downstairs was running as that would have been sub 19C before and even lower 18C range, even on a higher max ASHP LWT.

i decided to push the max LWT up to 41.5C to see if that pushed downstairs up enough. Rooms are 19.6C to 19.7C this morning. Its quite a cooler morning with OAT of 4C. Comparatively to when upstairs would clink off with the hestmiser, this is far better performance than seen before.

upstairs however is cooking. And I’ve got to point of lockshields almost being completely closed (1 8th to 1 10th of a turn left) and it’s still getting above 21C on the landing. I’ll adjust the LWT back slightly and continue with the lockshields as that’s definately had a positive effect on the cycling.

This however hasn’t been fruitless as it seems to indicate there’s 2 real issues.

1 the ASHP cycling too much, if I was relying on the heatmiser panel, and upstairs kept turning off completely downstairs would really struggle. the heat dump concept from the heat specialist reduced that. But doing it via lockshields instead of TRVs helped far further. Thanks Ian and Toodles for this.

2 - rad sizing. If downstairs still can’t come up to temp, it would seem obvious the rads are an issue. Thanks Derek for looking at calcs.

Only thing I notice is upstairs rads tend to get up to 1C more into them. Obviously lockshields have perhaps pushed that around now and seeing more balance with downstairs but the tall rad in main bathroom gets 32C quite often. Slightly higher than downstairs. But suspect that’s expected with lockshields etc.

The architect pointed out issues with the calcs in terms of room sizing. Living room ceiling heights were 0.5m lower in the calcs than actual. That’s 20% off. Also the hall didn’t have a complex/vaulted rating. That’s going to be pushing a lot of heat upstairs. So suspect that Calc is too low. This could be where seeing a problem across the system for these rads to get the temps out. For context both rooms are around 28sqm with 2.6m ceiling heights. I also suspect other factors such as there’s 2 log burners with external vents (due to hetas regs) that could also effect heat loss.

I don’t believe upstairs has sizing issues. So I wonder if delta20 wasn’t really that far off and downstairs is suffering simply because room volumes are off in the calcs

I’ll push for the rad increase as done everything can to run at expected LWT and avoid cycling and still not getting the temps to 21C downstairs. Its a real shame as essentially 1.5C off this being fine. But that 1.5C is very noticeable in these large spaces.

thanks again for everyone’s help on this.

@crimson The next stage might be to fit the larger radiators downstairs; this will have several benifits, not only will it heat downstairs more efficiently but you will also be able to lower the LWT thus helping to ‘normalise’ the temperatures upstairs. The balance of heat up and downstairs will improve matters all round - and perhaps the short cycling will be reduced into the bargain! Regards, Toodles.

Thanks Toodles, I hope so for sure.  That 1.5C max uplift to LWT puts about 1C extra into the system at current temps, and really felt that upstairs.  We had to have windows open last night (we prefer around 18.5-19C at night, and this is 20.5-21C).  I'm trying at the last possible point on the lock shields bar my office and towel rads.  Will also try the landing rad too down a bit as that's affecting adjacent rooms for sure.  But think be very hard to balance that against downstairs as is.

I'm at point of giving ceiling fans ago that we had installed (we were thinking of the ever heating up summers).  They can run in reverse.  Might see in living rooms if that does anything.

Thankfully this is all as clear as day now, with all the probes around, it's black and white.  This is where the heat miser panels are not indicative.  Upstairs shows 20.8-21C.  Downstairs, 20.5C.  Previously plumbers would say that's close, and bang on about setbacks and run it low and slow (yet they decided to smash up the LWT).  But if you have rooms at 19.5-19.8C downstairs with TRVs on max and lock shields fully open, and upstairs lock shields almost shut (and have had windows open overnight), and rooms are still around 21C, then obviously something is very amiss.

@crimson When the radiators downstairs are up-rated and the LWT is lowered, you will find the upstairs lockshield valves are a little less tricky to tweak as the lower temperature will effectively reduce the heat arriving at the valves a little. Regards, Toodles.

Thanks Toodles.
Here's probably a stupid question.

I notice:

• (Grant panel) LWT on Grant panel (I think this never shows .5C rounded to nearest 1) - 36C 
• (Plant room) LWT just going into LLH - 34.7C
• (Plant room) LWT just before zone valves - 34.5C (used as base temp)
• (Living 2) - highest temp at TRV side pipe - 30.7C (3.8C drop)
• (Living 1) - highest temp at TRV side pipe - 31.4C (3.1C drop)
• (Landing) - highest temp at TRV side pipe - 32.6C (1.9C drop)
• (Main bathroom) - highest temp at TRV side pipe - 32.5C (2C drop)

Is this the case of some kind of passive heat loss in pipes etc?  Just curious about the 2C drop from just before zone valves to warmest TRV side readings, and then an almost 4C drop to the rad in the most problematic regions.

@crimson Are the pipes in areas outside of your ‘living envelope’, in other words, any runs outside of your living spaces, utility area, outside plant room etc., insulated adequately? It rather sounds like a lot of heat loss to me. I’m sure Derek will have a better idea of the losses you might expect under well insulated circumstances but it sounds excessive to me. Pipes within your living environment may be thought of as part of the emitters and not necessarily insulated but again, if they run under ground floor areas, they should be insulated. Upstairs pipework tends not to be insulated though. (Just import a cat or two, they will soon show you where the warmest floors are!) Regards, Toodles.

Just thinking about the ground floor pipework, we had our pipe runs insulated with foam material that is split and slips over the pipes; I suspect that modern insulation would show an uprating on what we have though. We have the ground underfloor area of the property Q-Bot insulated and this certainly reduces heat loss through those pipe runs. Regards, Toodles

Posted by: @toodles

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@crimson Are the pipes in areas outside of your ‘living envelope’, in other words, any runs outside of your living spaces, utility area, outside plant room etc., insulated adequately? It rather sounds like a lot of heat loss to me. I’m sure Derek will have a better idea of the losses you might expect under well insulated circumstances but it sounds excessive to me. Pipes within your living environment may be thought of as part of the emitters and not necessarily insulated but again, if they run under ground floor areas, they should be insulated. Upstairs pipework tends not to be insulated though. (Just import a cat or two, they will soon show you where the warmest floors are!) Regards, Toodles.

From photos I have of when the project was in progress looks like the pipe work is in the ceilings, plastic, then runs down the walls are metal.  Those then are behind 75-100mm of celotex internal insulation.

@crimson pipes acting as radiators can be the issue accounting for temperature drop, but also flow rate.

That plastic pipe in your picture, hard to be sure but looks like it is 15mm. 15mm plastic has a much narrower bore than 15mm copper. That makes it harder for water to go through it , resulting in flow rate and balancing issues.   If this pipe is serving just one radiator its fine (provided its not too long). But if its serving a group of radiators then it will be constraining the flow rate to that group , and result in what you are seeing.

what radiators does this pipe serve? do you have any other information about the pipework, particularly to the problem zone / rooms downstairs?