Guinness
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| posted on 10/8/09 at 06:21 PM |
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Plumbing Help
Right, as some of you may be aware, I'm in the middle of a loft conversion of our Victorian Terrace.
Just had the plumber here for the third day fitting new rads, shower, pumps etc.
We've fitted 3 new rads in the loft (bedroom, ensuite and shoe room!), these are all significantly higher than the old header tank for the c/h
system.
So this is what we had:-
 
Central Heating Before
Initially the plumber said that the pump would just pump the water round the pipes to the new rads........
That obviously didn't work, so he's now relocated the central heating header tank, from the loft above existing bathroom, into the void
above the new bedroom (right in the top of the roof).
So this is what we have now:-
 
Central Heating Now
(Excuse the crapness of my paint drawing, but I really can't be arsed to CAD it all up!)
So the tank is as high as it will go. The 22mm vent, 22mm overflow and the 15mm return and cold water supplies have all been extended from their
positions in the space above the old bedroom, past the new rooms and up into the roof.
I've fired the central heating up tonight, and it's not working right. Basically the rads on the ground floor heat up OK, as does the one
in the old bathroom. The one in the bedroom next door to the bathroom gets tepid and the one in the front 1st floor bedroom is stone cold.
The rads in the attic are all stone cold too.
However the 22mm vent from the airing cupboard up to the tank in the very top of the house is red hot. And water is flowing straight up there and
emptying into the tank. From there I assume it's going back down the return as the level isn't getting any higher and it isn't going
down the overflow.
The central heating pump is on 1 of 3 (the lowest setting). If I turn the pump up to 3, all that happens is the amount of water coming out the vent
into the tank increases in volume and temp!
So, it seems to me that the water in the central heating circuit is taking the route of least resistance and shooting up the 22mm pipe, rather than
circulating through all the 15mm and the rads.
So, can I change the point where the 22mm vent comes from, to one of the 15mm pipes feeding the rads on the top floor???????????
Like this:-
 
Central Heating Proposed
Any help, advice would be gratefully received. (New 1/2 of Guinness is due to arrive on Sunday and the fact that we haven't moved into the new
attic, which means that I haven't even started on the nursery is causing me some domestic unpleasentnes!).
Mike
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Macbeast
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| posted on 10/8/09 at 06:33 PM |
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Get rid of the CH header tank and install expansion vessel ?
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thegasmen
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| posted on 10/8/09 at 06:35 PM |
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plumbing problems
Now then young man how are you been up scotland lateley
It could be simply that the system has an air lock.First of all shut down all the radiators on both sides of the valves and then open up them one by
one starting from the ones that didnt work making sure that the heating is on and running when you feel that the radiator is warming then move on to
the next untill they are all on. Then you may have to ballance the system let me know if you are unsure how to balance the system.
Regards Mick
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Guinness
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| posted on 10/8/09 at 07:08 PM |
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Macbeast
That was what I suggested to the plumber after his initial "the pump will just pump it round" statement was found to be incorrect.
He said it would be easier to relocate the tank...........
However that's now taken him all day and it still doesn't work.
How hard would it be for me to fit an expansion vessel??
Mick, no trips to Scottingland for me until the bairn arrives!
I've closed all the rads off, apart from the ones in the loft and run the heating system. No air locks that I can find..... Bled all the rads
OK.
How do I balance the system?
Mike
Mike
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SteveWalker
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| posted on 10/8/09 at 07:10 PM |
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No you can't move your vent pipe as shown in the third diagram. It should be within six inches of the 15mm feed into the system from the header
tank and both should be within a few feet of the pump inlet.
If you consider how the system works, the pump forces water around the system. All the water that is pumped by the pump is replaced by water returning
from the radiators via the boiler. There should be no flow in the feed or vent pipes. The feed pipe should allow expansion of the hot water (and any
air) to push a little water back into the tank and replace it as it cools and contracts. The vent is there to allow air to escape from the system and
water/steam in the event of a blocked feed and boiling water, thus preventing a steam explosion. As the vent is on the suction side of the pump there
should be no pressure to force water to take that route.
Just a silly thought, has the pump been removed for any reason? It may have been replaced pumping in the wrong direction.
Just looked at you diagrams again and noticed something - it may just be your drawing though. The original system is shown as fully pumped (all
radiators are fed from one pipe and return through another), but the new section is shown as single piped (both connections on a radiator are to the
same pipe and flow within the raidiator relies on different temperature water having different densities).
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Guinness
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| posted on 10/8/09 at 07:15 PM |
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Sorry Steve,
Pump is as it's always been. Well I say always been, since I replaced it about 3 years ago....... (Did I / could I have put it on upside
down?????)
The rads upstairs are fully pumped, just didn't draw all the connections / pipes when I was in paint.
So if I can't relocate the vent / return pipe
Thoroughly pissed off now.
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rachaeljf
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| posted on 10/8/09 at 07:20 PM |
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Hi there,
It looks like the flow is going through the hot water circuit, which has much less resistance than the radiator circuit. If your drawing is correct
that is the only way it would pump up the vent and into the header tank.
Firstly I suggest you insert a gate valve in your hot water circuit to throttle it down.
Then, with the hot water circuit shut off by your motorised valve (i.e set to heating only), balance the radiators to get adequate flow through the
topmost radiators. Start by fully opening both the balancing (not normally adjustable) and the hand adjustable valves to all the radiators. Then
follow the balancing procedure as per...
http://diydata.com/projects/centralheating/balancing/radiator_balancing.php
Once that is done, set your motorised valve to feed both heating and hot water. Then gradually close your heating circuit gate valve until water stops
coming out of the vent pipe. Then close the valve another quarter turn or so to make sure you have no unwanted flow up the vent pipe.
Don't be tempted to relocate or put any restriction in the vent pipe.
Hope that helps, cheers R
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thegasmen
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| posted on 10/8/09 at 07:32 PM |
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heating probs
Agree with rachael
Its sounds to me that you still have an air lock some where in the system thats stopping it heating properly run heating with all radiators open fully
turning heating off and then on each time try venting the pump to try and clear the trapped air once the air has realised itself you will find it in
a radiator or it will find its way up the feed an expansion then balance the system.
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Guinness
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| posted on 10/8/09 at 07:54 PM |
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Thanks guys
It's far too hot to have all the radiators on at the minute!
I'll try balancing them when it gets a bit cooler.
I don't have a motorised valve, just a lever, like a brake balance lever, which goes from heating to hot water, or some combination in
between!
I've been trying to get the system working with the hot water off, and the valve fully over to heating?
Cheers
Mike
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will121
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| posted on 10/8/09 at 08:04 PM |
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firstly concern is what was the plumber thinking in the first place as it was never going to work and to say the pump will pump it round! well! is the
heating system vent/fill pipe connection on the suction side of the pump? be carefull if the heating system is continuios pumping over the vent and
circulating, if has lead to failure of plastic header tanks in the roof with disarterious results
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Guinness
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| posted on 10/8/09 at 08:09 PM |
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quote:
Originally posted by will121
firstly concern is what was the plumber thinking in the first place as it was never going to work and to say the pump will pump it round! well! is the
heating system vent/fill pipe connection on the suction side of the pump? be carefull if the heating system is continuios pumping over the vent and
circulating, if has lead to failure of plastic header tanks in the roof with disarterious results
Heating is off now, with just the hot water on. I can't tell if the vent pipe is on the right side of the pump. They all disappear through the
floor in the bathroom. Uplifting the floor is not an option at the minute.
Mike
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coozer
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| posted on 10/8/09 at 08:12 PM |
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Mike, is the boiler a combi?
1972 V8 Jago
1980 Z750
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eccsmk
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| posted on 10/8/09 at 08:17 PM |
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u2u sent
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Guinness
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| posted on 10/8/09 at 08:28 PM |
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Steve, no the boiler is a 100 years old.
Eccsmk, u2u'd back. Rads upstairs are on twin pipe system, just me being lazy not showing them.
How do I shift an air lock then??
Mike
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Wheels244
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| posted on 10/8/09 at 08:56 PM |
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Mike
I know this probably doesn't help - but I would get a plumber in who knows what he is doing as it doesn't sound like yours does.
Are you paying the guy or is it a favour ?
If you're paying him, you shouldn't have to touch the system yourself.
[Edited on 10/8/09 by Wheels244]
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rachaeljf
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| posted on 10/8/09 at 09:54 PM |
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Sounds like your "motorised" valve is being pushed open by the pump pressure, allowing water through the hw circuit. As I said, if your
drawing accurately reflects your hw/ch circuits, that is the only way water can be pumped up the vent pipe. If your pump was fitted back to front I
think you would pump water back up the feed pipe into the header tank and start drawing air down the vent pipe, with unpleasant results.
As Mick said, you may have an air lock in the upper floor radiators, which will cause trouble. You might need a few rounds with your bleed key to get
all the air out.
Cheers R
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tegwin
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| posted on 11/8/09 at 08:03 AM |
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Sounds like you plumber is on something....
He should have insisted you had a pressurised heating system, and ideally should be using a thermal store and direct feed (mains pressure) hot
water.... That would be the prefered way of doing things
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