ASHP - most radiators not getting warm after install
Discussion
Old oil boiler replaced with a Mitsubishi ASHP, install completed today.
Also had 2 additional radiators fitted, in parallel with 2 existing ones.
Hot water is fine, new radiators get hot, but all the original radiators only get warm over the bottom few inches. Both pipes are warm.
All radiators have been bled, no more air coming out.
I've bled the pump by using the auto function, and via the scew (Evosta 3 DAB), and tried all the speeds. I've tried different operating modes.
I've tried it with all the TRVs fully open.
I've closed the TRVs and lockshields on the 2 new radiators.
I can't figure out why radiators that were working fine on the old boiler up until Monday lunchtime are now only getting warm about 20% of the way up, but the new radiators are warm all over?
The plumber finished yesterday, leaving the electrician to wire everything up and set it running. Electrician obviously knew next to nothing about plumbing, and left site as soon as the first radiator started to get warm
Also had 2 additional radiators fitted, in parallel with 2 existing ones.
Hot water is fine, new radiators get hot, but all the original radiators only get warm over the bottom few inches. Both pipes are warm.
All radiators have been bled, no more air coming out.
I've bled the pump by using the auto function, and via the scew (Evosta 3 DAB), and tried all the speeds. I've tried different operating modes.
I've tried it with all the TRVs fully open.
I've closed the TRVs and lockshields on the 2 new radiators.
I can't figure out why radiators that were working fine on the old boiler up until Monday lunchtime are now only getting warm about 20% of the way up, but the new radiators are warm all over?
The plumber finished yesterday, leaving the electrician to wire everything up and set it running. Electrician obviously knew next to nothing about plumbing, and left site as soon as the first radiator started to get warm
clockworks said:
Old oil boiler replaced with a Mitsubishi ASHP, install completed today.
Also had 2 additional radiators fitted, in parallel with 2 existing ones.
Hot water is fine, new radiators get hot, but all the original radiators only get warm over the bottom few inches. Both pipes are warm.
All radiators have been bled, no more air coming out.
I've bled the pump by using the auto function, and via the scew (Evosta 3 DAB), and tried all the speeds. I've tried different operating modes.
I've tried it with all the TRVs fully open.
I've closed the TRVs and lockshields on the 2 new radiators.
I can't figure out why radiators that were working fine on the old boiler up until Monday lunchtime are now only getting warm about 20% of the way up, but the new radiators are warm all over?
The plumber finished yesterday, leaving the electrician to wire everything up and set it running. Electrician obviously knew next to nothing about plumbing, and left site as soon as the first radiator started to get warm
If water is coming out and is clear and with a good spirt then a basic assumption would be that it's not a sludge or pressure issue. Next guess is that if some new rads have been added is that it could be balancing. Also had 2 additional radiators fitted, in parallel with 2 existing ones.
Hot water is fine, new radiators get hot, but all the original radiators only get warm over the bottom few inches. Both pipes are warm.
All radiators have been bled, no more air coming out.
I've bled the pump by using the auto function, and via the scew (Evosta 3 DAB), and tried all the speeds. I've tried different operating modes.
I've tried it with all the TRVs fully open.
I've closed the TRVs and lockshields on the 2 new radiators.
I can't figure out why radiators that were working fine on the old boiler up until Monday lunchtime are now only getting warm about 20% of the way up, but the new radiators are warm all over?
The plumber finished yesterday, leaving the electrician to wire everything up and set it running. Electrician obviously knew next to nothing about plumbing, and left site as soon as the first radiator started to get warm
If you shut off the new rads can you get more heat into the original ones?
Obviously, the plumber needs to return and do his job but in the meantime it might be worth going through the usual balancing motions.
If he’s just plumbed it in and buggered off before it was even powered on then doubt he’s going to be able to set it up properly.
See if he can sort the immediate issue and then find someone who knows what they’re doing to check and tune it so it runs properly without costing a fortune. Heatgeek website worth a try.
See if he can sort the immediate issue and then find someone who knows what they’re doing to check and tune it so it runs properly without costing a fortune. Heatgeek website worth a try.
CorradoTDI said:
Did the existing rads not need replacing with larger ones anyway?
Very odd that they left without fully testing and balancing the rads - this is the most important bit!
I'd not get rid of the oil tank yet!!!
2 rooms needed more heating, the rest were OK for the lower flow temperature.Very odd that they left without fully testing and balancing the rads - this is the most important bit!
I'd not get rid of the oil tank yet!!!
The easiest way to get more heat in those 2 rooms was to add a second radiator. One room already had spare tails, the other had another radiator added by teeing off the original one, right next to it.
Both of these new radiators get hot across the whole surface. If I close the lockshield valves down on both of these, open 3/4 of a turn, the other radiators in these 2 rooms warm up properly.
These rooms are the furthest away from the heatpump and associated gubbins.
Whatever I do (basically shutting off every other radiator), I cannot get the bathroom, hallway and second bedroom radiators hot across the whole surface, even if it's the only open radiator.
These are the closest radiators to the heatpump.
They all get hot at the bottom, and the flow and return pipes are hot. The water just will not circulate to the top of these radiators. I've tried them with the lockshields fully open, and cracked open one turn. No air in them.
I'm trying to get my head around the low-loss header setup, and the 2 programmable pumps - one on the heating flow up into the loft, the other on the primary circuit of the heatpump just before the 3 port valve for the hot water cylinder/heating circuit. There's also a 2 port valve just before the secondary (heating circuit) pump.
Seems like the heating water might be taking the "easy" path through the low-loss header pipe?
I'm struggling to see why it has a low-loss header, not a simple automatic bypass valve.
I asked the plumber who installed it, and I don't think he knew what it did, apart from "hydraulic separation of the primary and secondary circuits"
Low loss header is totally different to an abv if the t'd rad in on anything less than 15mm it's like not got enough flow
But I'm sure a few of us had doubts about this install the other day
You shouldn't need to touch it other than maybe the weather comp curve
It's their responsibility to set it up right and it to meet or exceed the figures they put in the documentation
But I'm sure a few of us had doubts about this install the other day
You shouldn't need to touch it other than maybe the weather comp curve
It's their responsibility to set it up right and it to meet or exceed the figures they put in the documentation
All rads are 15mm copper, except the bathroom which is 15mm plastic. All the runs are existing from the old system, and worked fine with the old boiler.
From what I can make out, the low-loss header is plumbed vertically across the flow and return, and would act as a bypass if all the rads were shut down? I assume the idea is that the vertical column of water in the header (between the flow inlet/outlet pair and the return inlet/outlet pair) keeps the flow and return separate under normal operating conditions?
It looks like a length of 38mm copper, with staggered pairs of ports top and bottom, and what I assume is an automatic bleed valve on the top, and a drain cock on the bottom.
Is there anything else inside it?
From what I can make out, the low-loss header is plumbed vertically across the flow and return, and would act as a bypass if all the rads were shut down? I assume the idea is that the vertical column of water in the header (between the flow inlet/outlet pair and the return inlet/outlet pair) keeps the flow and return separate under normal operating conditions?
It looks like a length of 38mm copper, with staggered pairs of ports top and bottom, and what I assume is an automatic bleed valve on the top, and a drain cock on the bottom.
Is there anything else inside it?
I suspect the old rads are blocked up and only got hot as the bottom part was much hotter when you had oil.
The fact the new rads get hot and none of the other do seems to confirm this.
How old is the old system ?
With a new and I assume expensive heat pump ( that by the sounds of it has been turned on not commissioned I suspect the cost of all new rads will be insignificant as a %.
My mother had blocked rads and no end of flushing ever got them clear.
The fact the new rads get hot and none of the other do seems to confirm this.
How old is the old system ?
With a new and I assume expensive heat pump ( that by the sounds of it has been turned on not commissioned I suspect the cost of all new rads will be insignificant as a %.
My mother had blocked rads and no end of flushing ever got them clear.
Jeremy-75qq8 said:
I suspect the old rads are blocked up and only got hot as the bottom part was much hotter when you had oil.
The fact the new rads get hot and none of the other do seems to confirm this.
How old is the old system ?
With a new and I assume expensive heat pump ( that by the sounds of it has been turned on not commissioned I suspect the cost of all new rads will be insignificant as a %.
My mother had blocked rads and no end of flushing ever got them clear.
3 of the radiators that aren't getting hot all over are relatively new:The fact the new rads get hot and none of the other do seems to confirm this.
How old is the old system ?
With a new and I assume expensive heat pump ( that by the sounds of it has been turned on not commissioned I suspect the cost of all new rads will be insignificant as a %.
My mother had blocked rads and no end of flushing ever got them clear.
Kitchen 8 years
Lounge 1.5 years
Bathroom just 3 months old
The bathroom radiator is a full height vertical towel rail, fed from the bottom
https://www.bestheating.com/milano-bow-anthracite-...
Only the complete bottom section and the first bar of the second section is getting hot.
The temperature difference between the hot and cold parts is very distinct. Bottom part is nicely warm, bordering on uncomfortable to the touch. Moving fingers up just one "ring" and it is stone cold.
It is like this even if all the other radiators are closed off.
Makes no sense to me. The radiator is 3 months old, no air in it. Heat isn't even rising up to the higher parts by convection or whatever.
Something that may be relevant:
The system wasn't drained completely when the ASHP was fitted. It was drained at the boiler, so the rising pipework up to the "manifolds" in the loft (bungalow with a small dormer conversion) and the horizontal pipes would have been emptied, along with whatever came out of the upstairs radiators before "vacuum" stopped them draining down.
The bleed valve on one upstairs radiator was opened during draining.
The system was refilled with a glycol mix, pumped in via a couple of connections on the primary circuit.
The system was then bled at each radiator by the plumber, but the system not run - no power at this time, so no pumps running
Both of the new radiators, and the rising pipework would have been completely filled with the fresh glycol mix. The existing radiators, holding a lot of the original water/inhibitor, would only have got a smallish amount of fresh glycol mix.
The electrician connected everything up the following day, and ran it to the point where the first rad started to get warm, and left site.
Is it possible that the 2 different fluids in the radiators have remained "stratified", so that only the fresh glycol mix is actually flowing around, leaving the old water/inhibitor mix in the upper parts of the existing radiators "stagnant"?
In our system we have UFH everywhere, however in our insulated double garage we have 2 x rads for burst of heat when needed in there, two big 1400mm twin finned ones. They provide a similar heat spread as yours. They get warm at bottom and half way up the middle but rarely full coverage.
For us though, they are so big and we don't need that much heat due to good insulation, that's fine.
It concerns me they didn't replace all your radiators, rules of thumb with ASHP is they only work with Good levels of insulation, they only work if setup to run low and long.... And they only work with big heat emitters.
Can you post up pics of your radiators?
Did the installer commission the system? Ie setup weather compensation? Provide you instructions on its use?
The radiators should also never feel hot... The flow temp should be around 50 degrees maximum as an outlet temp, ideally mid 40s. Your oil boiler probably ran at 70 degrees odd.
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff