New boiler installed, now I can only get one radiator at a time working

Mr_s

ThisIsWeird said:

Yes, the diverter valve (it diverts between CH and instant DHW) is built in to a combi boiler, as is the pump.
(I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)
As suspected above, this is most likely a balancing issue. You can heat up any one rad to 'hot' by closing off others?
When they carried out the chemical clean, they most likely opened up all the valves fully so's each rad had a good flow through them. If so, they should have noted how far open each lockshield was.
Mr S, could you check a few rads at random? Pull off the lockshield valve covers and tape a wee paper flag to the spindle, say pointing outwards. Now turn the spindle clockwise until it stops - that's it fully closed. Note down for each rad you check how many turns and part turns this takes.
Please report back, and it might give us a clue.
(Mention which rads, which rooms, where located, and how far/close to the boiler.

I've already messed with the locksheid valves trying to balance the system as a resort the other week trying to get things flowing. I followed a YouTube video. Closed all of the rads, fully opened the furthest from the boiler and opened the closest to the boiler just a quarter of a turn, then each subsequent rad from the boiler a little bit more than the last. I've managed to get all 4 upstairs luke warm but everything downstairs is stone cold no matter how much I persevere with it. 

Mr_s

FreeBear said:

ThisIsWeird said: (I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)

Modern boilers are complex beasts with lots of menu options. On my boiler, there is a menu option for selecting a pump response curve. Not changed it as the default appears to be working fine.

yeh. mine has a demand setting which controls the speed. It was on full so that's where I've left it

FreeBear

Mr_s said:

ThisIsWeird said:

Yes, the diverter valve (it diverts between CH and instant DHW) is built in to a combi boiler, as is the pump.
(I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)
As suspected above, this is most likely a balancing issue. You can heat up any one rad to 'hot' by closing off others?
When they carried out the chemical clean, they most likely opened up all the valves fully so's each rad had a good flow through them. If so, they should have noted how far open each lockshield was.
Mr S, could you check a few rads at random? Pull off the lockshield valve covers and tape a wee paper flag to the spindle, say pointing outwards. Now turn the spindle clockwise until it stops - that's it fully closed. Note down for each rad you check how many turns and part turns this takes.
Please report back, and it might give us a clue.
(Mention which rads, which rooms, where located, and how far/close to the boiler.

I've already messed with the locksheid valves trying to balance the system as a resort the other week trying to get things flowing. I followed a YouTube video. Closed all of the rads, fully opened the furthest from the boiler and opened the closest to the boiler just a quarter of a turn, then each subsequent rad from the boiler a little bit more than the last. I've managed to get all 4 upstairs luke warm but everything downstairs is stone cold no matter how much I persevere with it.

Opening up the radiator at the far end was the first mistake, second was opening up the other lockshields by quarter turns. Shut off all lockshields, and starting at the closest to the boiler, crack open the lockshield a little at a time. Monitor the temperature difference between flow & return, aiming for (nominally) a 10°C difference. Go slow, take your time. It will take a few minutes for the temperature to change as the lockshields are opened up.

Once the first radiator is done, move on to the next. By the time you get to the last radiator, you might be open a full turn.

One of a pair of cheap thermometer modules I use -

ThisIsWeird

FreeBear said:

ThisIsWeird said: (I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)

Modern boilers are complex beasts with lots of menu options. On my boiler, there is a menu option for selecting a pump response curve. Not changed it as the default appears to be working fine.

Ok, I was surprised that MrS was able to change the pump speed with such seeming ease. I couldn't begin to do that on my own boiler, and I fitted the damned thing.

If MrS's boiler has a Smart pump, then it should ideally be set to an auto-response option, so it can cope equally happily with either one or all rads needing a flow.

How did you adjust the pump flow, MrS?

Mr_s

FreeBear said:

Mr_s said:

ThisIsWeird said:

Yes, the diverter valve (it diverts between CH and instant DHW) is built in to a combi boiler, as is the pump.
(I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)
As suspected above, this is most likely a balancing issue. You can heat up any one rad to 'hot' by closing off others?
When they carried out the chemical clean, they most likely opened up all the valves fully so's each rad had a good flow through them. If so, they should have noted how far open each lockshield was.
Mr S, could you check a few rads at random? Pull off the lockshield valve covers and tape a wee paper flag to the spindle, say pointing outwards. Now turn the spindle clockwise until it stops - that's it fully closed. Note down for each rad you check how many turns and part turns this takes.
Please report back, and it might give us a clue.
(Mention which rads, which rooms, where located, and how far/close to the boiler.

I've already messed with the locksheid valves trying to balance the system as a resort the other week trying to get things flowing. I followed a YouTube video. Closed all of the rads, fully opened the furthest from the boiler and opened the closest to the boiler just a quarter of a turn, then each subsequent rad from the boiler a little bit more than the last. I've managed to get all 4 upstairs luke warm but everything downstairs is stone cold no matter how much I persevere with it.

Opening up the radiator at the far end was the first mistake, second was opening up the other lockshields by quarter turns. Shut off all lockshields, and starting at the closest to the boiler, crack open the lockshield a little at a time. Monitor the temperature difference between flow & return, aiming for (nominally) a 10°C difference. Go slow, take your time. It will take a few minutes for the temperature to change as the lockshields are opened up.

Once the first radiator is done, move on to the next. By the time you get to the last radiator, you might be open a full turn.

One of a pair of cheap thermometer modules I use -

thanks for that feedback. Ill get myself a thermometer and this week and give it a better go. What would you do about the TRVs? Leave them as is at sort of 3 ish or turn them up to 5 for balancing?

ThisIsWeird said:

FreeBear said:

ThisIsWeird said: (I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)

Modern boilers are complex beasts with lots of menu options. On my boiler, there is a menu option for selecting a pump response curve. Not changed it as the default appears to be working fine.

Ok, I was surprised that MrS was able to change the pump speed with such seeming ease. I couldn't begin to do that on my own boiler, and I fitted the damned thing.

If MrS's boiler has a Smart pump, then it should ideally be set to an auto-response option, so it can cope equally happily with either one or all rads needing a flow.

How did you adjust the pump flow, MrS?

And I didn't adjust the pump flow. But I'm able to access the settings on my boiler via a digital display which allow me to do so if desired. 

FreeBear

Mr_s said: Ill get myself a thermometer and this week and give it a better go. What would you do about the TRVs? Leave them as is at sort of 3 ish or turn them up to 5 for balancing?

Get two thermometers at least - That will save on swapping just one from pipe to pipe. Those modules are not very expensive. However, calibration is not brilliant, so you need to make a note of what each one reads in "free air" and do a bit of math if the numbers are not the same. Accuracy is not important as it is the relative difference in temperature between flow & return that is important.

TRVs need to be set to max or the heads removed completely whilst balancing the radiators.

ThisIsWeird

Mr_s said:

FreeBear said:

Mr_s said:

ThisIsWeird said:

Yes, the diverter valve (it diverts between CH and instant DHW) is built in to a combi boiler, as is the pump.
(I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)
As suspected above, this is most likely a balancing issue. You can heat up any one rad to 'hot' by closing off others?
When they carried out the chemical clean, they most likely opened up all the valves fully so's each rad had a good flow through them. If so, they should have noted how far open each lockshield was.
Mr S, could you check a few rads at random? Pull off the lockshield valve covers and tape a wee paper flag to the spindle, say pointing outwards. Now turn the spindle clockwise until it stops - that's it fully closed. Note down for each rad you check how many turns and part turns this takes.
Please report back, and it might give us a clue.
(Mention which rads, which rooms, where located, and how far/close to the boiler.

I've already messed with the locksheid valves trying to balance the system as a resort the other week trying to get things flowing. I followed a YouTube video. Closed all of the rads, fully opened the furthest from the boiler and opened the closest to the boiler just a quarter of a turn, then each subsequent rad from the boiler a little bit more than the last. I've managed to get all 4 upstairs luke warm but everything downstairs is stone cold no matter how much I persevere with it.

Opening up the radiator at the far end was the first mistake, second was opening up the other lockshields by quarter turns. Shut off all lockshields, and starting at the closest to the boiler, crack open the lockshield a little at a time. Monitor the temperature difference between flow & return, aiming for (nominally) a 10°C difference. Go slow, take your time. It will take a few minutes for the temperature to change as the lockshields are opened up.

Once the first radiator is done, move on to the next. By the time you get to the last radiator, you might be open a full turn.

One of a pair of cheap thermometer modules I use -

thanks for that feedback. Ill get myself a thermometer and this week and give it a better go. What would you do about the TRVs? Leave them as is at sort of 3 ish or turn them up to 5 for balancing?

ThisIsWeird said:

FreeBear said:

ThisIsWeird said: (I'm surprised you were able to adjust the pump speed - that's usually controlled by the boiler itself?)

Modern boilers are complex beasts with lots of menu options. On my boiler, there is a menu option for selecting a pump response curve. Not changed it as the default appears to be working fine.

Ok, I was surprised that MrS was able to change the pump speed with such seeming ease. I couldn't begin to do that on my own boiler, and I fitted the damned thing.

If MrS's boiler has a Smart pump, then it should ideally be set to an auto-response option, so it can cope equally happily with either one or all rads needing a flow.

How did you adjust the pump flow, MrS?

And I didn't adjust the pump flow. But I'm able to access the settings on my boiler via a digital display which allow me to do so if desired. 

Impressed! I presume considered an 'engineer setup' process? Do you know if there's a 'Smart' pump option?

Anyway, re balancing, I had to decipher mil's 7-zone UFH last year as the actuator heads had been mixed up - drove us crazy trying to figure out what was wrong with it! And being UFH, you often couldn't tell for hours which zone was actually heating up. Then I recalled the IR 'gun' thermometer my son had brought back from Uni, that they'd been using to monitor them all during COVID. What a boon - it detected the warming floors within 20 minutes. 
And it provided instant readings of the F and R temps for each zone by aiming at the pipes going to the manifold, to help with adjusting the flows for each zone. Strikes me as being ideal for this use - one trigger pull aimed at each pipe, and instant temp readings obtained.

FFHillbilly

Mr_s said:

FFHillbilly said:

if the OP can get any of the radiators working by isolating the others, I'd say there has to be blockage somewhere. system cleaner, followed by a flush would be my suggestion.

They have signed off to say they've done a chemical flush but not a power flush. The chemical flush was in with the price. 

just because they've said they have done it doesn't mean it was done thoroughly, and seeing as you said they were there and did it all in day it's very unlikely.  what you have described sounds exactly like a blockage. there isn't enough flow to be able to supply all radiators at once, but individually they are ok.
I have dealt with similar problems, well I got my plumbers to sort it, they spent a few hours sussing it out, then put some system cleaner in and left it for a few days for it to dissolve the blockage, then came back drained and flushed the system and refilled it with new water and inhibitor and the problem was solved. 
if you have a magnet cleaner check that both the taps are fully open, if one or both is closed slightly this could exibit the same problem as a blockage

ThisIsWeird

Ah! Good point!
MrS, you'll have a magnetic filter fitted? Could you check that to see how much, if any, sludge has been captured? That should give a very good idea of the state of your system.

Mr_s

ThisIsWeird said:

Ah! Good point!
MrS, you'll have a magnetic filter fitted? Could you check that to see how much, if any, sludge has been captured? That should give a very good idea of the state of your system.

Yeh I've got a magnetic filter fitted.

Would it have captured much if I haven't really had the heating running since install?