New boiler, rads keep getting cold

[Mrs Naylir]

Hi we had a baxi18 installed June. From day one the plumber could not get all rads hot and to stay on. They came back and changed pump, no difference changed all trvs. Now, the problem is this They all come on and are hot after about 45mins one goes cold and does not come back on . There are two that come on and work as they should. The bathroom comes on and cools down alot but is hot on left trv side cold on right. The others soon cool down and only heat up a bit. Now I realise trvs work on ambient temperatures but my lovely old system never went off with the westherm trvs these are tower it is a conventional system. The plumber is a lovely lad but I rang him and asked what it could be and he said he didn't know when they came back on the 3rd occasion they got them all going but went before they went off. We have now paid for the new system, new pump and trvs. Cant keep paying out. We are elderly and stressed. They seemed to struggle balancing it as as soon as one warmed up another went off and they rebalanced and then another went cold. Any ideas

 

[Scott_D]

Did you have TRVs before?
Could it be a one pipe system?

 

[Deleted member 120897]

Did you have TRVs before?
Could it be a one pipe system?

my lovely old system never went off with the westherm trvs these are tower

It still seems like a balancing issue, all depends on how quickly they’re balancing them. If they’ve had to replace the pump and trv’s at your cost then it suggests to me they don’t really know what they’re doing - nice lad or not.

 

[Scott_D]

It still seems like a balancing issue, all depends on how quickly they’re balancing them. If they’ve had to replace the pump and trv’s at your cost then it suggests to me they don’t really know what they’re doing - nice lad or not.

True
But often if a system is that difficult to balance its due to bad design.
Multiple rads in micribore
Old rad pipes linked together under boards
Single pipe or part single pipe etc etc

Things that should never have worked but somehow did and a sight alteration throws it all out.

 

[Mrs Naylir]

Did you have TRVs before?
Could it be a one pipe system?

Yes for 30 years no problems till new boiler installed. It is 2 pipe system

 

[SJB060685]

So no new rads installed and worked fine before?
Was the system flushed during the installation?

 

[John.g]

Hi we had a baxi18 installed June. From day one the plumber could not get all rads hot and to stay on. They came back and changed pump, no difference changed all trvs. Now, the problem is this They all come on and are hot after about 45mins one goes cold and does not come back on . There are two that come on and work as they should. The bathroom comes on and cools down alot but is hot on left trv side cold on right. The others soon cool down and only heat up a bit. Now I realise trvs work on ambient temperatures but my lovely old system never went off with the westherm trvs these are tower it is a conventional system. The plumber is a lovely lad but I rang him and asked what it could be and he said he didn't know when they came back on the 3rd occasion they got them all going but went before they went off. We have now paid for the new system, new pump and trvs. Cant keep paying out. We are elderly and stressed. They seemed to struggle balancing it as as soon as one warmed up another went off and they rebalanced and then another went cold. Any idea

What make are the TRVs?

Were they replaced with the same make?.

Is the boiler still firing when they don't come back on?

Even though TRVs have a very small temperature hysteresis (ambient temp difference between fully open and fully shut) of around 1.5C to 2C they are still or should be relatively slow acting due to the volume of fluid in their actuators, they should not just act in a on/off manner, at least mine don't, presently using EPH make but did have Myson nd a few other types and all worked similarly and maintain very reasonable room temperatures as long as the boiler is firing continuously or cycling on/off in the case of a oil fired boiler.
I have them installed horizontally on the rad returns to sense a more representative room temperature and also, even though they are all bi-directional, installing them horizontally ensures that the water flow is "proper" ie from under the valve seat.
Of course if installed vertically on the rad flow (as most are) then flow is proper as well whether they are uni or bi directional.

 

[John.g]

Also just check that the actuators are properly attached to the valve body, ensure actuator fully opened ie anticlockwise to index 5 or whatever then ensure knurled nut fully (hand/finger) tightened (clockwise).

Also read somewhere that some TRVs had chromium bodied actuators (normally plastic) which were transferring the heat by conduction from the water in the rad and obviously would then take hours to reopen after closing off, no good.

 

[Mrs Naylir]

What make are the TRVs?

Were they replaced with the same make?.

Is the boiler still firing when they don't come back on?

Even though TRVs have a very small temperature hysteresis (ambient temp difference between fully open and fully shut) of around 1.5C to 2C they are still or should be relatively slow acting due to the volume of fluid in their actuators, they should not just act in a on/off manner, at least mine don't, presently using EPH make but did have Myson nd a few other types and all worked similarly and maintain very reasonable room temperatures as long as the boiler is firing continuously or cycling on/off in the case of a oil fired boiler.
I have them installed horizontally on the rad returns to sense a more representative room temperature and also, even though they are all bi-directional, installing them horizontally ensures that the water flow is "proper" ie from under the valve seat.
Of course if installed vertically on the rad flow (as most are) then flow is proper as well whether they are uni or bi directional.

New trvs Tower. Old ones westherm. Boer doesn't go on and off plumber says that's OK.

 

[Deleted member 123817]

If the boiler is still firing then the heat must be going somewhere.
If you open the TRVs fully will the rads that weren't heating then heat up?

 

[Mrs Naylir]

Sadly no. One won't heat at all. Two are fine and the rest go off but heat up slightly. If i put them on 5 they will heat up for a while but cool off again too much. Apart from the one in utility room which won't go back on again, till whole system has been switched off. I really appreciate your help. We are so upset amd stressed over this. We wish we had stuck with our old system.

 

[Deleted member 120897]

What’s the boiler thermostat set to?

 

[Mrs Naylir]

What’s the boiler thermostat set to?

80

 

[Mrs Naylir]

What’s the boiler thermostat set to?

80

 

[Mrs Naylir]

So no new rads installed and worked fine before?
Was the system flushed during the installation?

 

[Mrs Naylir]

So no new rads installed and worked fine before?
Was the system flushed during the installation?

One new rad no trv in hall. Had a magna flush

 

[Deleted member 120897]

One new rad no trv in hall. Had a magna flush

Are you able to turn the hall one down on both sides?

 

[Mrs Naylir]

Are you able to turn the hall one down on both sides?

There's no trv on it. Sorry to be daft but my Husband 80 and I am in my 70s and we really don't know how to do that. The one that goes off and stays off is in the next room to hall. Pipe on keft where trv is , is very hot. Boiler id in a cupboard in this room.

 

[SJB060685]

Out of curiosity how old is the original part of the system? It's possible, although I'm not saying it is for sure that during the change over and flush you desturbed a lot of sludge that wasn't fully removed from the system and is causing some issues.

 

[Mrs Naylir]

Out of curiosity how old is the original part of the system? It's possible, although I'm not saying it is for sure that during the change over and flush you desturbed a lot of sludge that wasn't fully removed from the system and is causing some issues.

Pretty old put in in 1991. Never had a problem. You could well be right as a couple of rads get hot on left and not so hot on right. We did ask for a power flush but he said the magnet one was better. They vibrated the rads with some gadget. He said power flush could fracture pipes

 

[SJB060685]

Installing a magnet is mandatory on any new/replacement boiler these days and thats not open for debate. To say a system doesn't need a powerflush and the magnet alone is enough is really quite naive.

 

[Deleted member 120897]

Oh ok, wasn’t sure how able you were. If you want this resolved I’d say there’s 2 choices:

1. Get original installer back to sort properly
2. Obtain a different engineer and pay for it to be sorted

If you go down route of 2nd choice, I’d be inclined to pursue costs from original installer.

 

[Mrs Naylir]

Installing a magnet is mandatory on any new/replacement boiler these days and thats not open for debate. To say a system doesn't need a powerflush and the magnet alone is enough is really quite naive.

Thank you. Looks like we will have to get another plumber. As I said very nice lad but he doesn't know what the problem is. Not long in the profession.

 

[SJB060685]

One indication of large sludge build up in the system is to get a strong magnet and offer up to the copper pipework in several places. Copper cannot be magnetised but if there was magnetite (sludge) in the system the magnet would adhere to the copper.

 

[Deleted member 120897]

Installing a magnet is mandatory on any new/replacement boiler these days and thats not open for debate. To say a system doesn't need a powerflush and the magnet alone is enough is really quite naive.

Could it have been a magnacleanse machine?