Thanks for all your replies
We now have boiling hot radiators upstairs.
I tried to bleed the downstairs radiators and managed to get warm water to one
When I bleed the downstairs no air is released but water spurts out across the
room as if under pressure.
Should I still try the forced bleeding or could this be sludge.
Yes, still try forcing each downstairs rad. It is possible that there is
some trapped air in the supply pipes, which is not getting to the rads and
so cannot be bled out. By providing a bit more "urge" you will hopefully
shift this to a rad so that it can be bled out.
I have been away for the last two days (work) and left my girlfriend confined to
upstairs rooms (she's got a telly and I bought her
a hot water bottle, I know how to treat a girl!!!)
I am going to try forcing the radiators and balancing them tomorrow before I
start do you think that I should replace the 'y' valve
as a precaution.
On Thu, 4 Dec 2003 11:41:22 -0000, "Roger Mills"
There *could* be a problem with that - but it seems unlikely because at
least *some* of the radiators are getting hot. They wouldn't be if the
mid-position valve had failed in the HW position. I wouldn't replace it
unless the forcing exercise fails - and, even then, it may not be the
I have drained the system and replaced two faulty radiator valves, refilled and
tried forcing the downstairs radiators but now I
have no heat at all.
The boiler continues to come on for around 30 seconds, go off for about a minute
and come back on again for 30 seconds.
This cycle continues the whole time that the system is running.
I have hot water.
Could it be the thermostat on the boiler? If so can I change it or does it need
On Fri, 5 Dec 2003 10:07:18 -0000, "Roger Mills"
If the domestic hot water is being heated by the boiler, it's *not* the
boiler stat. It seems that the hot water from the boiler is only getting to
the indirect coil in the hot water cylinder, and not to the radiators. This
being the case, the hot water heat exchanger can only absorb (it appears)
about one third of the boiler's heat output - hence the boiler only runs for
one third of the time, and cycles on its thermostat. This is what you would
expect it to do in the summer - but not in the winter!
I am assuming, from what you have said earlier that you have a Y-plan
system. [Have a look at Y-plan in
http://content.honeywell.com/uk/homes/systems.htm and see whether your
system is like this].
For the radiators to get hot, the following conditions need to be fulfilled:
* Central Heating must be on at the Programmer/Time Switch
* The room stat must be calling for heat (i.e. must be set for a higher
temperature than the current temperature of the room where it is situated
* The mid position valve must be working correctly (and must be in either
the Mid or CH - but not HW position)
* each radiator must have a clear flow and return path to the boiler with no
The non-fulfillment of any one of these conditions is sufficient to stop the
heating from working. The first two are very easy to check. The mid position
valve probably has a manual lever on it which, when operated, forces it to
the mid position. Operate the lever and hold it on for a few minutes (it
will probably spring back if you let go of it). See if the radiators then
get hot, and report back.
My hunch is that you've got air locks in your system - probably made worse
by draining the system to replace the radiator valves.
Before I continue I fogot to tell you what happens when I close all but one
The pipe to the downstairs radiator gets hot but the radiator remains cold.
When the bleed valve is opened water spurts about a
metre across the room.
The boiler now stays on for just 10 seconds.
The Y-valve is fully electronic (sealed unit) one and from the outside seems to
On Sat, 6 Dec 2003 17:05:36 -0000, "Roger Mills"
On Sat, 06 Dec 2003 17:24:06 +0000, firstname.lastname@example.org wrote:
As Roger says, if the DHW is working then the symptoms that you
describe point to something preventing reasonable circulation through
the CH system. The impact of that would be to create the short
boiler runs since the implication is that the room stat is causing
Either this has to be air in the system, (although closing off all
radiators except one should create enough pressure to force it out of
the way), or some obstruction. The upstairs radiators working
before and the downstairs not could simply have been the piping
You could eliminate the valve by taking the head off and operating it
manually. The cam underneath should turn relatively freely.
The other thing could be sludging, but generally that comes on
Was this something where the system was working and now suddenly
doesn't? It is quite common for motorised valves to fail for one
reason or another at the start of the heating season for example......
To email, substitute .nospam with .gl
We have just bought the house, we moved in a couple of weeks ago and the
upstairs radiators worked when we moved in but the
downstairs ones didn't.
We turned off the radiators upstairs and managed to get heat downstairs for one
day and then the whole system stopped.
We turned the radiators back on upstairs and after 24 hours we had hot radiators
There is hot water in the pipes on both sides of the y-valve
There is also hot water in the pipes to radiators downstairs but the radiators
remain completely cold.
When we turned the radiators off upstairs we discovered (when water came through
the kitchen ceiling) that there was a leak from the
bathroom valve, hence the need to drain the system today.
Luckily the weather hasn't been too cold but we have no other form of heat in
the house so this remains a priority.
Thanks for the help
On Sat, 06 Dec 2003 18:42:19 +0000, email@example.com wrote:
Having read what you have said, your replies to Roger, etc., it seems
pretty clear that the flow in parts of the system is not what it
Having the pipes hot on both sides of the Y valve tells you that there
is *some* flow but not how much. A very small flow will create
exactly what you describe - boiler on for short periods, hot water as
far as one side of the radiators.
The scenario of upstairs radiators *were* working and now are not
could be because of air in the pipes following draining or because the
motorised valve is not opening fully (could be either part). In the
latter case it could easily be that the heating had not been used much
before you moved in and now has become progressively worse and stuck.
When you turned all radiators off bar one, did you check that the
lockshield valve on that radiator was full open? If not, it's
possible that the system is way out of balance and needs to be
It is also possible that the system is heavily sludged up and you have
moved the sludge around when you drained it. Was there sludge as you
drained or was the water very rusty in colour? You could check
this out by draining down again and taking a downstairs radiator off
the wall. Carefully drain first and then use containers under the
unions. Sludgy water is an indellible dye - be careful.
If you find a lot of sludge in the radiator then there's a fair chance
of a lot in the pipes too and that is then your culprit.
Based on the premise that the system worked OK last winter and doesn't
now, then my gut feel is tha the valve is now the most likely
contender. After checking the lockshields it's where I would look
next. Did you try taking the head off of the base and turning the
To email, substitute .nospam with .gl
There's something odd going on in your system. I'm not sure that we're going
to get to the bottom of it - and you may have to get a "professional" to
look at it.
The only final thing I can suggest is to bleed a *lot* of water out of each
downstairs rad to ensure that *neither* flow nor return pipe is airlocked.
With the system not running, turn off both valves and remove the bleed
screw. Open one of the valves and catch the water in a bucket. When the
bucket is half full, close the first valve and open the other one. Collect
another half bucket from the bleed hole. [If nothing comes out when only one
valve is open, you definitely have an air lock or blockage].
When you've caught sufficient water, close the valve, replace the bleed
screw. Then open both valves and test the system.
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