Another Rad Problem

Aeneas

I have several rad problems
1) one of the 10 rads downstairs does not work. All the other nine (including three double rads) are hot ie you cannot keep your hand on them for more than three or four seconds. One of these needs constant venting, but the venting works. The air is expended with some force until the water spurts out.
2) most of the 5 rads (incl. one double rad) upstairs do not get hot. They are warm ie you can keep your hand on them indefinitely. When I try to vent the upstairs rads some air comes out slowly but no water, as if there were no pressure in the system.
3) the hot water tank upstairs seems fine.
Does anyone have a possible explanation for the fact that the rads upstairs are warm only and don't vent properly?

JamesM

Aeneas wrote: »

I have several rad problems
1) one of the 10 rads downstairs does not work. All the other nine (including three double rads) are hot ie you cannot keep your hand on them for more than three or four seconds. One of these needs constant venting, but the venting works. The air is expended with some force until the water spurts out.
2) most of the 5 rads (incl. one double rad) upstairs do not get hot. They are warm ie you can keep your hand on them indefinitely. When I try to vent the upstairs rads some air comes out slowly but no water, as if there were no pressure in the system.
3) the hot water tank upstairs seems fine.
Does anyone have a possible explanation for the fact that the rads upstairs are warm only and don't vent properly?

Short answer - after midnight - If no water comes out upstairs - not enough water in the system. If it is a sealed system, look for the fill valve. If it is an open system, check the water level in the header tank in the attic (not the big one). If there is water in it, then a valve is turned off or the pipe down from it is blocked.
Jim.

Aeneas

Thanks. It's an open system with a small tank in the attic. I will check it but I'm not quite sure what you mean that "if there is water in it" - shouldn't there be water in it at all times?

JamesM

Aeneas wrote: »

Thanks. It's an open system with a small tank in the attic. I will check it but I'm not quite sure what you mean that "if there is water in it" - shouldn't there be water in it at all times?

There should be water in that tank, but the ballcock can stick in the up position and the tank can dry up. If there is water in the tank, but no water coming out of the rads, then there is a blockage in the pipes down from the tank, or a valve turned off.
Jim.

Hotblack Desiato

Is there a zone valve, i.e. downstairs and upstairs are separate zones which the controller can operate independently? The controller could be set to operate the downstairs zone only, or the valve could be stuck.

JamesM

ninja900 wrote: »

Is there a zone valve, i.e. downstairs and upstairs are separate zones which the controller can operate independently? The controller could be set to operate the downstairs zone only, or the valve could be stuck.

There is no water coming from the upstairs rads when he bleeds, so there is not enough water in the system. The problem is almost certainly the header tank or the pipe coming down from it.
Jim.

Aeneas

JamesM wrote: »

There should be water in that tank, but the ballcock can stick in the up position and the tank can dry up. If there is water in the tank, but no water coming out of the rads, then there is a blockage in the pipes down from the tank, or a valve turned off.
Jim.

Thanks Jim. I've been away and only managed to get into the attic today. The small header tank was half full of water and the ball-cock seemed to work fine. I checked that the valve on the outlet pipe (at about 18ins from the tank) was open and it was. I then inserted a length of wire into the outlet pipe to a distance of about four or five feet and worked it around a bit. There was no obvious consequence for the header tank ( eg no blow back of air or sudden rush of water out) but when I subsequently vented the rads upstairs they vented normally and all except one are now hot. The exception is a double rad in a bedroom where the panel nearest the wall is fairly hot but the panel into the room is only warm. I don't suppose I have finally solved our problem, but then neither have the three plumbers I have asked to look at it over the past year. And none of them suggested it was a blockage in the pipe from the tank. In case the problem returns I would like to know a) if there is an easy way to check if a blockage from the tank is indeed the problem? b) where does the pipe from the tank normally join the heating system? (I imagine this would be the best place to check? c) as a matter of curiosity how come hot water is not pumped back up to the header tank in the attic?. Forgive my ignorance but plumbing is obviously not my strong point.

JamesM

That's great, it looks as if you moved something to let some water through. Are there 2 vents in the double rad that's not heating or does the one near the wall do both panels ? Does water come out ?
The answer to a) is: there's a blockage if no water comes out an upstairs vent when you bleed. If that is happening, then you could open the feed pipe from the header tank down in the hotpress (I don't know your system, but this is the norm).
There are 2 pipes going to the header tank from where the heating pipes connect to the coil in the cylinder. The 2 pipes come up through the floor, one branches in to the top coil connection in the cylinder, and continues up to the attic and hangs over the header tank. The second pipe is the return to the boiler. It branches in to the bottom coil connection, and continues up to the bottom of the header tank - the one you put the wire into. If you disconnect this pipe where it branches into the cylinder or somewhere just above this point, you will tell if the water is getting through - and get wet :eek: and it can be black filthy gunge - so be careful - don't do it unless you are really stuck.
Your last question - sometimes if the pump is too strong, you will get water going up the overflow to the header tank - that's why the overflow pipe is there. Last word: Dont go at it anymore than you have to - if it is working, leave well enough alone
JIm.

Aeneas

JamesM wrote: »

That's great, it looks as if you moved something to let some water through. Are there 2 vents in the double rad that's not heating or does the one near the wall do both panels ? Does water come out ?
The answer to a) is: there's a blockage if no water comes out an upstairs vent when you bleed. If that is happening, then you could open the feed pipe from the header tank down in the hotpress (I don't know your system, but this is the norm).
There are 2 pipes going to the header tank from where the heating pipes connect to the coil in the cylinder. The 2 pipes come up through the floor, one branches in to the top coil connection in the cylinder, and continues up to the attic and hangs over the header tank. The second pipe is the return to the boiler. It branches in to the bottom coil connection, and continues up to the bottom of the header tank - the one you put the wire into. If you disconnect this pipe where it branches into the cylinder or somewhere just above this point, you will tell if the water is getting through - and get wet :eek: and it can be black filthy gunge - so be careful - don't do it unless you are really stuck.
Your last question - sometimes if the pump is too strong, you will get water going up the overflow to the header tank - that's why the overflow pipe is there. Last word: Dont go at it anymore than you have to - if it is working, leave well enough alone
JIm.

That is very helpful. The double rad upstairs has only one vent - one of those little brass nuts that you open with a screwdriver (and that wears pretty quickly) surrounded by a plastic collar with a tiny spout in it out of which the air and water flow. After my work on the header tank it vents normally now. The inner panel nearest the wall is quite hot but the outside panel is not as hot - just warm. But it is sufficient to heat the bedroom (unless, maybe, the weather gets colder). Maybe this is where I should leave well enough alone, although the situation puzzles me.
2) I am generally happy now with the situation upstairs. But I still have a problem downstairs where I have 9 rads. Two of these present problems. One, in a small bedroom, has been out of action for some time, but this has not been a problem from a heating point of view because the room takes heat from the rest of the house. But more recently a second rad, one of two radiators in the kitchen, has started acting up. For the past while it used to get warm at the top but stayed cool at the bottom. Today it is completely cold. When I vent it there is no air, but water seeps out. The pipe with the regulator knob on it is cold, the other is lukewarm. I am concerned that ithis rad will go the same way as the rad in the small bedroom and that I have some kind problem that will gradually extend to the other rads downstairs.
Any ideas as to what might be wrong and how I could rectify it.

JamesM

I would say bad circulation - circulating pump on slow speed or gunge building up in pipes, blocking them off. Is the system very old ? Are you sure that the lockshield valves, at the other end, are fully open.
Jim.

Aeneas

JamesM wrote: »

I would say bad circulation - circulating pump on slow speed or gunge building up in pipes, blocking them off. Is the system very old ? Are you sure that the lockshield valves, at the other end, are fully open.
Jim.

The system is seven years old. But I have always had problems of one kind or another. As soon as one is resolved another appears, as with my kitchen rad. But this morning it is warm!!!Sorry for being so ignorant, but what are lockshield valves?

JamesM

Aeneas wrote: »

The system is seven years old. But I have always had problems of one kind or another. As soon as one is resolved another appears, as with my kitchen rad. But this morning it is warm!!!Sorry for being so ignorant, but what are lockshield valves?

The're just the valves at the other end of the rad to the usual on and off ones. They usually can't be turned by hand - need a wrench or something. They should be checked to make sure that they are fully open if the flow is not good to a rad.
Jim.

Aeneas

JamesM wrote: »

The're just the valves at the other end of the rad to the usual on and off ones. They usually can't be turned by hand - need a wrench or something. They should be checked to make sure that they are fully open if the flow is not good to a rad.
Jim.

1) Before I do anything with the lockshield valves I just want to check that it would not affect the balancing?
2) Any idea why a rad might be stone cold one day, warm another and hot another without any apparent reason or intervention by me?

JamesM

Aeneas wrote: »

1) Before I do anything with the lockshield valves I just want to check that it would not affect the balancing?
2) Any idea why a rad might be stone cold one day, warm another and hot another without any apparent reason or intervention by me?

You want to effect the balancing of the system. You want to cut down the flow to the hotter rads and get the heat to the cooler ones. There may be a problem with the design of the system, but all you can do without professional help is to make sure that the pump is at its fastest and that both ends of the cooler rads are fully open and that the hotter rads are slowly closed off to try and get the hot water out to the cooler rads. The temp in the rads will change if other rads are turned on and off.
Jim.

Aeneas

JamesM wrote: »

You want to effect the balancing of the system. You want to cut down the flow to the hotter rads and get the heat to the cooler ones. There may be a problem with the design of the system, but all you can do without professional help is to make sure that the pump is at its fastest and that both ends of the cooler rads are fully open and that the hotter rads are slowly closed off to try and get the hot water out to the cooler rads. The temp in the rads will change if other rads are turned on and off.
Jim.

You might be right about needing professional help. But my confidence has not been helped by the three plumbers I have engaged up to now, none of whom solved the problem and all of whom came up with different opinions. One proposed that I install new piping to my whole system. Another that I enlarge the pipes from the boiler. They may be right but I have no way of knowing. And the one who suggested a complete refit didn't mention the possibility that my upstairs problem might be caused by a blockage. Come to think of it he didn't even look in the attic. In fact it was your advice about the blocked outlet that helped me resolve that issue with a coat hanger and a length of wire Things are reasonably ok at the moment and I am inclined to leave well enough alone. But in case they deteriorate maybe I could ask you two more questions
1) is balancing done using the lockshield valves or the normal on/off knobs?
2) following from this when you say to "slowly close off the hotter rads" do you mean using the lockshield valve or the on/off knob?

DublinWriter

Aeneas +1.

On my fourth plumber now, and what really surprised me was that every plumber has their own ideas about what would be the cause of a particular problem, and as Aeneas said, one even recommended that I re-plumb the entire house!

Again, as Aeneas said, you probably need to balance the rads using the lockshield valve on them.

Is the water in your area very hard? Your pipes&rads could be furred up inside. In that case you need to get a plumber to de-sludge your entire system and then put an inhibitor into it to prevent from further furring up.

JamesM

Back to what I said earlier - bad circulation. Seeing that it is only in 7 years, and has always given trouble, it is probably not gunge. More likely bad layout or, with 10 rads downstairs (that's a lot), pipes that are too narrow for the distance the water has to travel. A stronger circulating pump, or a 2nd pump somewhere around the system, might be a relatively cheap answer.

To balance the rads leave the ordinary knob turned on fully and close down the lockshield valves on the hottest ones bit by bit over a few days. If a hot one goes cool, just open the lockshield valve a small bit until it heats better. That's about all you can do yourself - you did check that the pump is at it's fastest speed ? (if there is an adjustment)
Jim.

Sparkpea

to get the one radiator heating thats not heating - turn off all the other radiators and check heat does get to that radiator so you can check its not a blocked pipe, then turn on the other radiators one by one gradually and check if the one downstairs is still heating, it could have been an airlock in the pipe and that has shifted it.

if not, check if one pipe is hot and the other isn't, there could still be an airlock and you might need to bleed the water through the valve - also does the pipes downstairs drop from above? if so this can cause problems withsome radiators heating and its a bit of a pain in the ass to fix but not impossible.

JamesM could be correct about the bad circulation - if the radiator is the last on the system then yes it may have trouble pumping around to it, try balancing down the lock shields on the radiators which heat first (depending on what way the system is piped).

If this fails the next thing to do is change the circulating pump - 9 times out of 10 this will fix the problem, if not then its possibly something more tricky.

good luck

Aeneas

Thanks for all this advice. At least it's got the system in some kind of shape again after several years of lukewarm rads. I've still got one cold radiator but it's in a small spare downstairs bedroom that gets sufficient heat from the rest of the house. Unless problems reappear (and this I think is likely) I am inclined to leave well enough alone. Happy Christmas.

311

Hello ,just to add to this before the thread disappears.
Your problem is the system is dirty and it is affecting the pumps impeller.

If you ever call a plumber ,recommend that he clean your heating system with a long term solution. Don't introduce a high powered cleaner as it might damage your system.

Chemicals that are of good quality are Sentinel.


Happy christmas

Sparkpea

_Brian_ wrote: »

Hello ,just to add to this before the thread disappears.
Your problem is the system is dirty and it is affecting the pumps impeller.

If you ever call a plumber ,recommend that he clean your heating system with a long term solution. Don't introduce a high powered cleaner as it might damage your system.

Chemicals that are of good quality are Sentinel.


Happy christmas

I have used Sentinel desludge remover for many years and agree it is great quality and probably the best - however i've recently been using a powerflusher to restore the system to its "new condition" and the results are a hell of alot better than Sentinel on its own - yes there is a slight risk that if there is a weakness in the sytem the powerflusher might find it however if the system is already pressurised then its not much different from that.

Happy Christmas

311

Sparkpea wrote: »

I have used Sentinel desludge remover for many years and agree it is great quality and probably the best - however i've recently been using a powerflusher to restore the system to its "new condition" and the results are a hell of alot better than Sentinel on its own - yes there is a slight risk that if there is a weakness in the sytem the powerflusher might find it however if the system is already pressurised then its not much different from that.

Happy Christmas

I have a fernox powerflow mark 2 ,the latest model. It doesn't always work ,sometimes a longer time scale is better.

Aeneas

Thanks guys for taking the trouble to write even on Christmas Day! Sentinel I presume is a liquid that is introduced into the system and works in a chemical way to unblock sludge. I presume the system has to be flushed to get it out.

311

Sentinel sludge remover can be left in for two weeks or more. We put it into old heating systems a week or so ,before we install a new boiler .
People always comment on how much hotter their heating systems get.

Sometimes though ,heating systems can have bad corrosion in a certain part of the heating system and sluge remover may cause damage.
Example would be a small leak in concrete that the dirt is holding together ,you really wouldn't want it to burst.

Personally ,I wouldn't add any chemicals if I wasn't sure of the condition of the heating system.A plumber would have a good idea of how to locate a leak due to corrosion ,if there was one. Which is one of two reasons why you get sludge to begin with .

theplumber

Corrosion causes thinning of steel and production of sludge.

The latest ultrasonic thickness gauge enables us to know precisely how thin the steel is. Therefore giving indication of amount of sludge.

and degree of risk of exposing pinholes when cleaning,
for specific info see radtesting.com

I do confess to both owning and writing this site..

311

theplumber wrote: »

Corrosion causes thinning of steel and production of sludge.

The latest ultrasonic thickness gauge enables us to know precisely how thin the steel is. Therefore giving indication of amount of sludge.

and degree of risk of exposing pinholes when cleaning,
for specific info see radtesting.com

I do confess to both owning and writing this site..

Radiators can be fine and pipework can be damaged .

Most people now what corrosion does ,it's the cause of the corrosion that would need to be fixed.

I service heating systems ,sometimes that are 20 years old. There is no corrosion whatsoever ,I don't need a machine to tell me either.

I can see people would be frightened into getting that test done ,it's still not full proof though.

theplumber

Brian I would certainly not try to frighten people into getting the test done.

It is more aimed at local authorities who are replacing radiators rather than cleaning systems when fitting new boilers.
This is a dreadfull waste of tax-payers money and energy resources.

Very little corrosion produces a lot of sludge whch often alarms and frightens people into replacing all their radiators.

Many radiators in skips are found to be well over 1mm thick.

I agree essential remedial work should address causes of corrosion.

311

theplumber wrote: »

Brian I would certainly not try to frighten people into getting the test done.

It is more aimed at local authorities who are replacing radiators rather than cleaning systems when fitting new boilers.
This is a dreadfull waste of tax-payers money and energy resources.

Very little corrosion produces a lot of sludge whch often alarms and frightens people into replacing all their radiators.

Many radiators in skips are found to be well over 1mm thick.

I agree essential remedial work should address causes of corrosion.

I had to take all the radiators out of a house and flush each radiator out individually ,couple of weeks back:(. Chemicals didn't work.

I'd say a lot of other plumbers would have recommended getting new radiators. Everything worked fine in the end.

ircoha

FAO theplumber

The website needs some work done on it: not much fun when all you get is 'main' when u click on most of the side tabs: corrosion maybe

This is also of interest

website design by www.webprospain.com all rights reverved 2007©

theplumber

Sorry about that perhaps I should have put one of those little mr men with a drill on it wearing a safety hat.

plumbersdiary.com has much of the content that will be on radtesting

I do hope that plumbers will learn from the content as I do when posting it.

Webprospain.com are very helpfull when database stuff is required us plumber can´t know everything. they would own copyright of certain elements of course.

311

theplumber wrote: »

I do hope that plumbers will learn from the content as I do when posting it.

The equipment you talk of is old ,it's been around for years.
If I was going to plug a site ,I'd make sure it looks well first to be honest.

People don't have the money to waste on stuff like that ,they just want their heating working.