Hi,

I am after a bit of advice about troubleshooting a central heating
problem. I am not an expert so some of my terminology may be incorrect.


>From what I can make out, the system is fully pumped & vented. The

problem is that when the system is on 'Hot Water Only', 3 of my
downstairs radiators get very hot. The motorised valve head unit is
clearly showing that it has shut off the radiator circuit. Adjusting
the manual bypass valve does not seem to make any difference.

What could my problem be? I thought perhaps it could be that the valve
itself is not operating even though the motorised head is, or that the
pump maybe running in reverse?

Does anyone have any suggestions for how I might fix it?

Thanks in advance.

AJJ.

AJJ wrote:

> Hi,
> 
> I am after a bit of advice about troubleshooting a central heating
> problem. I am not an expert so some of my terminology may be incorrect.
> 
>>From what I can make out, the system is fully pumped & vented. The
> problem is that when the system is on 'Hot Water Only', 3 of my
> downstairs radiators get very hot. The motorised valve head unit is
> clearly showing that it has shut off the radiator circuit. Adjusting
> the manual bypass valve does not seem to make any difference.
> 
> What could my problem be? I thought perhaps it could be that the valve
> itself is not operating even though the motorised head is, or that the
> pump maybe running in reverse?
> 
> Does anyone have any suggestions for how I might fix it?
> 
> Thanks in advance.
> 
> AJJ.
> 


Could you let us know if this is a new problem, i.e. has it only 
recently started occuring or has it always been this way?

It has been like this for quite a while. I replaced the pump & the
valve about a year ago and am fairly sure it started happening at that
point. The valve was certainly broken and the pump was so noisy I
replaced it at the same time.

AJJ

"Richard Conway"  wrote in message 
news:epUXe.47914$6J1.44237@fe07.ams...

> AJJ wrote:
>> Hi,
>>
>> I am after a bit of advice about troubleshooting a central heating
>> problem. I am not an expert so some of my terminology may be incorrect.
>>
>>>From what I can make out, the system is fully pumped & vented. The
>> problem is that when the system is on 'Hot Water Only', 3 of my
>> downstairs radiators get very hot. The motorised valve head unit is
>> clearly showing that it has shut off the radiator circuit. Adjusting
>> the manual bypass valve does not seem to make any difference.
>>
>> What could my problem be? I thought perhaps it could be that the valve
>> itself is not operating even though the motorised head is, or that the
>> pump maybe running in reverse?
>>
>> Does anyone have any suggestions for how I might fix it?
>>
>> Thanks in advance.
>>
>> AJJ.
>>
>
> Could you let us know if this is a new problem, i.e. has it only recently 
> started occuring or has it always been this way?


Classic symptom of the immersion reurn pipe not being connected to the 
heating return pipe "close" to the boiler.
Oher causes may also be considered.

I am not sure where the return pipes join but it is certainly not in
the vicinity of the hot water tank. I suspect it is close to the boiler
but cannot check it without having the room apart. If they join a
considerable distance away from the boiler is it possible the problem
was worsened by installing a new more powerful pump?

AJJ.

In an earlier contribution to this discussion,
AJJ   wrote:


> I am not sure where the return pipes join but it is certainly not in
> the vicinity of the hot water tank. I suspect it is close to the
> boiler but cannot check it without having the room apart. If they
> join a considerable distance away from the boiler is it possible the
> problem was worsened by installing a new more powerful pump?
>
> AJJ.


What you *mustn't* have is some radiators returning one side and some the
other side of the hot water return - they must all be on the *same* side -
otherwise you can can get reverse circulation through some of the rads.

If this problem started when you changed the 3-port mid-position valve, I
would be inclined to suspect that there is some crud in the valve which is
stopping it from closing off fully - allowing *some* CH flow in the HW-only
position.
-- 
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

There are certainly no radiators between hot water return and boiler.

I will take the valve out and check that it is closing properly.
That'll have to wait until I have time to drain the system It is quite
possible there is some crud in the valve as when I changed the pump it
was full of crud. So much so that I was amazed it was working at all.
The aperature size that was left for water to flow through was about 5
mm at best.

Thanks for the advice.

AJJ.