On Tue, 09 Dec 2003 17:21:52 GMT, Moonshine
wrote:


The Boiler is a GlowWorm FuelSaver 55F with a rated output between 35k & 55k
Btu/h. Its anyones guess as to what it has been set to. The manual talks about
putting a suppied self adhesive label by the data plate to record setting but
guess what I can't see one :-)

It doesn't matter greatly - this is a 10-16kW range and I would be
surprised if it is oversized for a house of this size. If you had
said twice this figure then I would have suggested looking further.




Yes it is 8mm Microbore (I put it in the Subject line but should have also
included it in the body text too for clarity sorry)


Sorry, I missed it in the subject line.





Have you checked for sludging?

What is the best way of doing this (i.e. least messy )

Before doing this, another thing to check is the motorised valve(s).
It could be that this is stuck or blocked. Try taking off the head
and turning the cam manually. You can also try operating the manual
lever on the valve. Sometimes the gearing mechanism in the head fails.
Any problems in this area and the general flow to the CH can be poor.
The fix is to replace the valve, which is an easy enough job..


Next, I would go round and open all of the lockshield valves fully and
check behaviour again. It could be that this is problem. If it
isn't, and there is a sludge problem then you will need to open them
all anyway.

To check for sludging and to resolve:

Pick a radiator where it is easy to get some old towels underneath
plus some polythene. A downstairs relatively smaller one is probably
better since fine sludge particles are likely to have collected more
so in lower radiators. You then need some containers to go underneath
each end of the radiator. I bought cat litter trays from the
supermarket. They're cheap, the right height and will take a fair
amount of water. You do need to take some care because sludgy water
is an effective dye.

With the heating off, turn off both valves on said radiator and
carefully undo one of the union nuts to let the water drain into one
tray, then undo the other. If you do it slowly, you can control the
flow easily. Undo the vent as well.
Once the water has stopped trickling out, lift and tip it to one end
and see if sludge comes out. If there is a fair amount, then you
will have pretty dirty water and sludge before this anyway.

Fasten small plastic bags over the radiator tails and take the
radiator outside. Give it a flush through with a mains hose or
pressure washer. With the radiator still off the wall, carefully
open each radiator valve and check that you are getting a respectable
flow of water. There may well be further sludge in the pipes if
there are long horizontal runs, but there should be enough head of
water from the feed tank in the roof (this is open vented system,
yes?) to flush out the pipes.

It will be reasonably clear if sludge has been the problem by this
time. If it is, then you need to repeat the exercise at each
radiator. Finally, give the system a good flush through with clean
water from the roof tank.

By this time, either because you opened the lockshields, resolved a
problem with the motorised valve(s) or with sludge, you should be able
to get reasonable flow on the pump mid and high settings. Before
my heating refurbishment, I had a 15-50 pump on an 8mm system and it
was fine.

If you have done the cleaning exercise, I would then put in some
flushing/cleaning agent and run the system hot for a week. Then
drain and flush again.

Once you've done all of this, then an Alpha pump may help further.
If I had still got the old system I would have replaced my pump with
one. As it was, I have one in my new boiler which is controlled by it
to match the heat output. However, I do have an Alpha on my separate
workshop circuit and that works well. The run from the house to the
workshop is quite long and the pipe resistance higher than for a
circuit purely within the house, so the extra head is a help.

However, before splashing out for one of these, I would check for the
more obvious things that are limiting flow first.



If you have TRVs especially, a better pump option could well be the
Grundfos Alpha. There is a 15-60 model of this which has a 6m max
head as opposed to the 5m of the UPS 15-50. It also adapts its
output to match the resistance requirements.

No TRV's


However, before doing a pump swap, I would check for why the
circulation is poor.




Cheers

Cliff

.andy

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..andy

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