So after some reading, thought I'd double check settings 2100 was set to 0, so WC isn't even on.  Will point this out to plumber who's coming later.  Not really sure why though it's not getting to temp with a fixed point of 50c and no WC on

Plumber couldn't make it - but passed Grant tech support to me.

We've now set:

21 00 - from 0 to 1

21 02 - set at 50c

21 03 - now set to 40

21 04 - set to -3 (my original post was incorrect, it was changed from -4 to -3 by plumber)

21 05 - now set to 25

We also checked the holding return and seeing 00 00 at 37c and 00 09 was 50c, and he remarked the house is taking a chunk of the heat out.

Not quite sure why downstairs refuses to heat up though.  I sent a photo to plumber showing the valves for the 3 main zones, upper and uf are midway, down is all way to right.

Those valves you show are either open or closed - there's no 'partially open' option. They should be in the 'auto' position (far right) but they have quite a bit of play in them, so maybe the 2 you mention are just naturally where they are. The lever would have to be in the manual notch on the far left to be overriding the system, and even then, manual means 'open'. The water is flowing down through those pipes to the heating isn't it?

You could upload more pictures to help. Is it a 'standard' Grant install with a Low Loss Header?  Where is the Grant controller located?  What other controls are being used?  Where in the country are you, and what outside conditions are you experiencing?   You say the radiators are sized correctly, but what type are they, and what was the design temperature?

You'll see in other topics that ASHPs can struggle in cold, damp, conditions.

Thanks for the reply Mike, plumber got me to switch to manual position on far right valve, I’m away tonight and tomorrow but will take photos Friday and ask other half how heating is tomorrow.

Found one photo I took before moving in, that's attached.

I believe there’s a low loss header from searching that and seeing it in plant room.

Control wise just been the main Grant panel, 4 heatmiser thermostat panels in the zones, and the 1 panel currently not working for hot water. No smart TRVs or anything like that, TRVs left at maximum. In terms of on/off temps on panels have kept those within 2c.

Based in Suffolk, outside has been -3 lowest lately. Frosty, damp and cold basically last few days.

Radiators:

Upstairs:

Stelrad compact with horizontal line style K1 type. Those matched the heat loss calls performed by plumbers, think mostly 1000x500 in size. 2 per room upstairs, 1 on landing. Think they’re rated at approx 750 watts a piece at D50, highest demand room is 470W, so 470 / 0.301 for d20= 1561, about there (0.301 was Stelrad’s correction factor)

Downstairs:

Eskimo column radiators, largest demand room is 1050 watts, in there are 2x1451x200 rads rated at 1320w each. Eskimos correction factor for D20 is 0.41, so 1050 / 0.41  = 2560 which the 2640 covers.

Bathroom has a Reina Florina towel rad and a Corex tall rad. En-suite a Reina Florina rad. All were checked at Delta20 with correction factors gains heat loss calcs

Property itself extensively renovated with all external walls having 75-100mm insulated inside added, roof insulation redone, all windows are triple glazed. Basically a lot done to insulate the property more.

Just finding it odd radiators barely feel warm in downstairs zone.

we have had 2 incidents, ashp and panel having no power due to suspected power cut and surge protection and now hot water panel no power. Also a plumber when installing a rad left the cap off the Low Loss Header which left us with a load of water in our utility, since then it’s been problematic.

Posted by: @crimson

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I have a 220sqm property with a Grant 13kW Aerona 3 ASHP installed as part of a full renovation/extension heating and plumbing redesign.

We moved in on 1st December and have never quite had the heating be up to scratch.

- can you clarify what this mean, please? Did you move into a property with the ASHP already installed (under a previous owner) or did you have the ASHP installed as part of the renovations?  Basically, I'm curious about when the installation took place (for you or for another owner) and is it new or old?

I can't pretend to follow the mass of pipework, but most components I can make out. On the pipework with the Mag One filter there should also be a flow limiter, set to whatever your design said the flow should be. Is that present? Is it maybe just above the filter? I'm assuming that just by the secondary pump is a diverter valve which switches between DHW and CH? I can't quite see it. Where on this picture are the three valves you showed us earlier?  

Posted by: @crimson

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Upstairs:

Stelrad compact with horizontal line style K1 type. Those matched the heat loss calls performed by plumbers, think mostly 1000x500 in size. 2 per room upstairs, 1 on landing. Think they’re rated at approx 750 watts a piece at D50, highest demand room is 470W, so 470 / 0.301 for d20= 1561, about there (0.301 was Stelrad’s correction factor)

Downstairs:

Eskimo column radiators, largest demand room is 1050 watts, in there are 2x1451x200 rads rated at 1320w each. Eskimos correction factor for D20 is 0.41, so 1050 / 0.41  = 2560 which the 2640 covers.

I'm no expert but I think you are using the correction factors incorrectly, your rads can't output more heat at a lower DT, so even if you do have a dT of 20 (which is unlikely with a heat pump).  The heat output of the rads upstairs is 750 x 0.301 = 225 x2 = 450 so is barely enough to heat the upstairs at DT 20.

If its more like DT10 then the output will be 0.15 of 750 = 112 x 2 = 225W so half what you need.

Posted by: @mikefl

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Posted by: @crimson

↑

I have a 220sqm property with a Grant 13kW Aerona 3 ASHP installed as part of a full renovation/extension heating and plumbing redesign.

We moved in on 1st December and have never quite had the heating be up to scratch.

- can you clarify what this mean, please? Did you move into a property with the ASHP already installed (under a previous owner) or did you have the ASHP installed as part of the renovations?  Basically, I'm curious about when the installation took place (for you or for another owner) and is it new or old?

I can't pretend to follow the mass of pipework, but most components I can make out. On the pipework with the Mag One filter there should also be a flow limiter, set to whatever your design said the flow should be. Is that present? Is it maybe just above the filter? I'm assuming that just by the secondary pump is a diverter valve which switches between DHW and CH? I can't quite see it. Where on this picture are the three valves you showed us earlier?  

Hi Mike, sorry wasn't clear.  Whole house project was a full renovation/extension project with the heating system done as part of it.

It's all brand new.

I'll take some more photos tomorrow and send them.  The 3 valves are near the bottom of the large tank on the left.

If you could annotate the photo with the points you're pointing out, I can then have a look and take more detailed photos.

Thanks again for taking the time with this

Posted by: @gary

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Posted by: @crimson

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Upstairs:

Stelrad compact with horizontal line style K1 type. Those matched the heat loss calls performed by plumbers, think mostly 1000x500 in size. 2 per room upstairs, 1 on landing. Think they’re rated at approx 750 watts a piece at D50, highest demand room is 470W, so 470 / 0.301 for d20= 1561, about there (0.301 was Stelrad’s correction factor)

Downstairs:

Eskimo column radiators, largest demand room is 1050 watts, in there are 2x1451x200 rads rated at 1320w each. Eskimos correction factor for D20 is 0.41, so 1050 / 0.41  = 2560 which the 2640 covers.

I'm no expert but I think you are using the correction factors incorrectly, your rads can't output more heat at a lower DT, so even if you do have a dT of 20 (which is unlikely with a heat pump).  The heat output of the rads upstairs is 750 x 0.301 = 225 x2 = 450 so is barely enough to heat the upstairs at DT 20.

If its more like DT10 then the output will be 0.15 of 750 = 112 x 2 = 225W so half what you need.

 

I'll raise this with the plumber (heating installers), thanks Gary.

Not sure why everything was indicated then to use DT 20, that would be a huge mistake on their part.  I have a heat calc document with everything listed but would rather not post here as has address details etc (Heat Engineer Software Ltd. document)

 @crimson Ignore my previous post not enough caffeine.

DT20 is possible but your heat pump is going to be running at a relatively high temperature so not very efficient.

if you are trying to heat to 21C and your rads are sized for DT20 then the average temp in the heating system needs to be 41C (i.e. difference of 20C).

To get an average of 41C with a heat pump the LWT will need to be higher than that so running at 45C.

From the settings you posted the heat pump is set to run between 40 and 50C depending on the outside temp, so it should be in the correct ball park.

However, if the heat loss assessment was accurate, if you are doing setbacks at night, lowering the temp, the house will never get to temp.  In this weather 2 to -3C my heat pump has to run 24/7 to keep the house at 21C if I turn it off the house cools down and I don't have any spare capacity in the heat pump to get it back up to temp.

Your heat loss assessment should have a design temp its probably 50C at -2 or -3C depending on your location that will give you DT20.

So the plumbers have probably done the assessment correctly at a relatively high design temperature, if you want the system to be more efficient you would need to reassess at a lower design temperature e.g. 40C then the DT would be smaller and the rads relatively larger to output enough heat.

@gary no problem I’m only getting my head round this. I did do the rad sizing with them back in June I think so am having to warm up some old cells.

at the moment it’s getting 50 in and 37 return. Seemingly does that imply not enough temp is coming out in the rads?

it’s a really odd one. I’d expect with the 50c temperature to see some rads feel warmer than they are but throughout the day it’s very inconsistent. The plumber did think maybe the hot water panel being out is causing the ashp to possibly put too much time on heating water but will see

@crimson with the flow and return temps you are getting they are very wide DT13, this suggests not enough flow rate in the heat pump circuit is there any way to tell what flow rate you have in the heat pump its usually in litres per min?

This would also make sense with your comment on the rads feeling warmer later in the day, as the outside temp increases heat pump will be able to raise the flow temperature higher if it was working at max capacity with a dT of 13.

I know on my heat pump if I drop the flow rate too low then the dT gets too wide at lower outside temps then the heat pump has to work really hard, using a lot of electricity to keep the dT relatively small, mine is currently running at flow 34C return 31C so dT3.