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Mrs Naylir

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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 said:
Did you have TRVs before?
Could it be a one pipe system?
Click to expand...
Mrs Naylir said:
my lovely old system never went off with the westherm trvs these are tower
Click to expand...
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.
 
Undertrained said:
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.
Click to expand...
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 said:
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
Click to expand...

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.
 
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.
 
John.g said:
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.
Click to expand...
New trvs Tower. Old ones westherm. Boer doesn't go on and off plumber says that's OK.
 
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.
 
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.
 
SJB060685 said:
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.
Click to expand...
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
 
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.
 
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.
 
SJB060685 said:
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.
Click to expand...
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.
 
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.
 
SJB060685 said:
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.
Click to expand...
Update. Got the engineer back. He looked at the one that comes on gets very hot and then goes off and stays off . He said trv was stiff took it off wiggle pin. It heated up. Of course he went and it switched off again. Others still cooling off quickly and only get a bit warm again. I am having to keep the couple that do work on 5 to get them to stay on. House thermostat never reaches its max. So house not too hot. These as I said are new Tower Trvs . Now my old trvs never turned the rads completely off stayed on all the time at the output we set. He said new systems are different I just want to cry. Surely the rads shouldn't get that cold for that long. Any advice
 
No they shouldn't. Under normal working conditions the trv's will stay open until target room temperature is met, whereby they throttle in. Was the new boiler sized correctly? As in is it's rated output the same as previous boiler?
 
SJB060685 said:
No they shouldn't. Under normal working conditions the trv's will stay open until target room temperature is met, whereby they throttle in. Was the new boiler sized correctly? As in is it's rated output the same as previous boiler?
Click to expand...
It was supposed to be a Baxi 18. When he came he asked me what it was I dont know how to check what he fitted we just trusted them
 
So he made no note of previous boiler output or did any heat loss calculations? The problem you're experiencing with rooms never coming up to temperature can be caused by an undersized boiler but I still think you have something else going on. Even if the new boiler was undersized you would still reach a certain indoor temperature, the fact you say rads warm up then go cold for ages suggests something else is going on as well.
 
SJB060685 said:
So he made no note of previous boiler output or did any heat loss calculations? The problem you're experiencing with rooms never coming up to temperature can be caused by an undersized boiler but I still think you have something else going on. Even if the new boiler was undersized you would still reach a certain indoor temperature, the fact you say rads warm up then go cold for ages suggests something else is going on as well.
Click to expand...
I think your right. Funny it worked when he took trv off. I told him it would go off after a bit permanently but he had to rush off. The boiler warranty says baxi 418 so I guess it is the right size our gut feeling is the cheap Trvs. He said all new systems go off completely. Because my Husband is elderly and so am I and female. He wont believe us. When I pushed him on why the trvs completely go off till rad is cold, he said it is hard to explain. He is such a nice guy but we have spent thousands, we are not wealthy and it looks like we will have to get in a new plumber and start again. He honestly, just does not know why it happens. Is it possible for trvs to be too sensitive to temperature levels. We can't be the only ones to ever have this problem
 
If all the TRVs are opened fully to index 5 they should stay full open until they are sensing a (room) temperature of 30C, so definitely something clearly wrong, they do shut off fully at the set temperature and have a very small hysteresis of a a degree or two but are fairly slow acting so are nearly always passing some water, they shouldn't open/shut rapidly.
 

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Thank you so much this what we thought but our plumber said the new systems don't work like the old my 30 year old ones never went cold. Do you know if Tower trvs are any good. Our rooms are nowhere near 30 degrees
 
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