brightspark
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screwfix do a wilo gold pump for about 39 quid. u might need new pump vaves mind there a pig to get off. there 6 quid a pair 
- Thread starter malcolm
- Start date
This does sound like a pump problem, even with it making a noise could be stuck,impellor detatched or just lazy!(when you switch the heating on you can usually hear the pump push water not just hum) So first thing would be change that, I wouldn't bother with a wilo, just get to plumb centre or silmilar and get a grundfos for price difference. If after that you've still got problems and assuming it is gravity system you could be looking at an anti gravity valve thats blocked or collaspsed(or some other blockage in pipework)
malcolm
& Clementine the Cat
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I've made a bit of progress. The upstairs radiators didn't have any water in them. I've bled them a few times and most of the air should be out of the system now. Couldn't find any bleed other than the radiators, but haven't had the floors up to look. Boiler sounds much quieter with some water in it.
Also replaced the pump and can hear water flowing through the pump now (couldn't before). It's slightly odd - the pump is set to pump downhill on the return pipe. Normally they are the other way around (uphill, supply).
Anyway, the radiators still don't work!
Valves are all open, there doesn't seem to be too much scum in the system. Wondering if there could be some sort of 3 way valve inside the boiler that isn't working. I'm a bit stuck now.
Also replaced the pump and can hear water flowing through the pump now (couldn't before). It's slightly odd - the pump is set to pump downhill on the return pipe. Normally they are the other way around (uphill, supply).
Anyway, the radiators still don't work!
Valves are all open, there doesn't seem to be too much scum in the system. Wondering if there could be some sort of 3 way valve inside the boiler that isn't working. I'm a bit stuck now.
brightspark
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gravity systems allways have the pump on the return back to boiler .its only fully pumped systems thats on the outgoing flow. and generaly pump is just below the 3 port valve in airing cupboard next to hw tank .make sure the pump is pumping the corect way theres generaly an arrow on pump flow back to boiler .turn boiler theremostat right up set pump speed to full . if any radiators get hot turn them off that will force the water down the other rads .if theres airlocks in pipes .try that
malcolm
& Clementine the Cat
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Thanks. On a gravity system would it be normal not to have any motorised valves? I sneaked off to look at the internet and it said air blockage, motorised valve, sludge or pump. I'll try switching the bathroom radiator off and see if I can get another one hot. Presumably go around like that until they all work?
the snooper
getting older by the day
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have you determined if its fully pumped or gravity
if its fully pumped then you should hear the pump as it heats the domestic hot water supply
if its fully pumped then you should hear the pump as it heats the domestic hot water supply
the snooper
getting older by the day
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malcolm
& Clementine the Cat
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Thanks for the link to the instructions - had another good read today. The pump only comes on for the central heating not the hot water. So the hot water is gravity. Is that the distinction?
Edit - a quick lookup - semi gravity looks likely. Looks exactly the same as the system in the first picture here: http://www.miketheboilerman.com/pipeworklayouts.htm
Edit - a quick lookup - semi gravity looks likely. Looks exactly the same as the system in the first picture here: http://www.miketheboilerman.com/pipeworklayouts.htm
the snooper
getting older by the day
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sounds like a strange one if you look at the parts list there is only one heat exchanger so i assume it does both dhw by gravity and radiators through pump so from that we can assume the heat exchanger is not blocked .
it may be worth a try at taking a radiator off the wall and trying to blow though it just to check if they are all blocked up.
youve certainly found a good one
it may be worth a try at taking a radiator off the wall and trying to blow though it just to check if they are all blocked up.
youve certainly found a good one
the snooper
getting older by the day
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hes just put a new one on it
brightspark
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no motorised valves on gravity. yes it generaly gets the airlocks out of system. if not its the last resort slackening a rad valve off a cold radiator till hot water comes through .then reconect it happens now and then
just a thought theres a bleed screw on new pump
malcolm
& Clementine the Cat
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Looked at the book that came with the pump and they seemed to be talking about bleeding off the screw that you undo to look at the impeller. I've left the instructions at the house so let me know if I've missed something - it's one of those Wilo Gold ones from Screwfix The whole thing was full of water before the top connection was tightened (bottom shut off valve was a bit leaky). Sounds like water is flowing when it's running, but it's not quiet so there's some air in the system.
John is over there just now. I've given him a call and asked him to turn the hot radiator off so we can try for a second one.
PS - good to rule out the valves - that makes it much easier not worrying about some valve I can't find. No wires to operate valves which ruled out external ones, but was worried there might be one inside the boiler (can't find it in the parts manual).
The whole thing was full of water before the top connection was tightened (bottom shut off valve was a bit leaky). Sounds like water is flowing when it's running, but it's not quiet so there's some air in the system.John is over there just now. I've given him a call and asked him to turn the hot radiator off so we can try for a second one.
PS - good to rule out the valves - that makes it much easier not worrying about some valve I can't find. No wires to operate valves which ruled out external ones, but was worried there might be one inside the boiler (can't find it in the parts manual).
hunter27
Pete
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A few things to think about
If the boiler is heating the hot water the problem is with the rad circuit. There is no divertor valve on your Thorn boiler just a simple pumped circuit either a 1 or 2 pipe system.
I think you said the pump is on the return pumping downward this is ok but not ideal as when any quantity of air arrives at the pump it starts to cavitate and often stops pumping, sometimes setting the pump to full speed and turning it on and off in surges helps (lots of gurgling and air noise is good to start with). only bleed the radiators with the pump stopped as it may also suck air in. concentrating on the radiator nearest above the pump.
We have sometimes had to reverse the pump direction just to get things working and then swap it back. As also mentioned there may be a gravity check valve (one way valve) fitted to the central heating flow pipe and these do have a habit of getting clagged up (looks like a long compression coupler) THIS WILL NOT LET YOU REVERSE THE PUMP IF ONE IS FITTED.
Who said plumbing was easy
Good luck
Pete
If the boiler is heating the hot water the problem is with the rad circuit. There is no divertor valve on your Thorn boiler just a simple pumped circuit either a 1 or 2 pipe system.
I think you said the pump is on the return pumping downward this is ok but not ideal as when any quantity of air arrives at the pump it starts to cavitate and often stops pumping, sometimes setting the pump to full speed and turning it on and off in surges helps (lots of gurgling and air noise is good to start with). only bleed the radiators with the pump stopped as it may also suck air in. concentrating on the radiator nearest above the pump.
We have sometimes had to reverse the pump direction just to get things working and then swap it back. As also mentioned there may be a gravity check valve (one way valve) fitted to the central heating flow pipe and these do have a habit of getting clagged up (looks like a long compression coupler) THIS WILL NOT LET YOU REVERSE THE PUMP IF ONE IS FITTED.
Who said plumbing was easy
Good luck
Pete
mike os
just a little insane.....
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Next
are there thermo valves on the rads?
If yes remove head & check the spindle in the valve body can move up & down, pliers help ( only moves4-6 mm)
turn off any working rads as you go
if all else fails connect a hose to the drainoff & backfill the system
are there thermo valves on the rads?
If yes remove head & check the spindle in the valve body can move up & down, pliers help ( only moves4-6 mm)
turn off any working rads as you go
if all else fails connect a hose to the drainoff & backfill the system
malcolm
& Clementine the Cat
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Good to hear the boiler doesn't have an internal valve - going to be just air and/or sludge then. Thanks for the tips.
Had a report back from John. He turned off the bathroom rad last night and the next one heated up. Turned that off and got another one going. Had to stop there because of a leaky valve.
I think we might drain the system at the weekend and replace some of the valves - they aren't thermostatic ones but I think John wants to fit those. We'll flush it with the cleaner stuff and try going around one rad at a time again.
Had a report back from John. He turned off the bathroom rad last night and the next one heated up. Turned that off and got another one going. Had to stop there because of a leaky valve.
I think we might drain the system at the weekend and replace some of the valves - they aren't thermostatic ones but I think John wants to fit those. We'll flush it with the cleaner stuff and try going around one rad at a time again.
the snooper
getting older by the day
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ive taken radiators ouside stuck a hose pipe in one end and give them a good few taps with a rubber mallet you soon start to see the gunge coming out
malcolm
& Clementine the Cat
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Thanks for all the help on this - we're nearly there. Changed the leaky valve upstairs and while we were at it we drained the system and put cleaning stuff in it. Success on all of the radiators apart from a couple of downstairs ones. 
Lots of little bubbles coming out of the bleed in those downstairs radiators so they must have been sucking a fair bit of air in from somewhere. In trying to back fill from a hosepipe we spotted a very leaky drain valve which will need to be changed. It's an odd one as it didn't appear to leak until a hose pipe was connected to try to push air up the pipes - then the leak was very obvious. Learning a lot about heating. Keen to save up a quarter of a million and get my own house to play with.
Looking like we'll get there eventually. Will need to find out how to balance radiators as fairly well all the valves have been backwards and forwards and have lost their original position.
Lots of little bubbles coming out of the bleed in those downstairs radiators so they must have been sucking a fair bit of air in from somewhere. In trying to back fill from a hosepipe we spotted a very leaky drain valve which will need to be changed. It's an odd one as it didn't appear to leak until a hose pipe was connected to try to push air up the pipes - then the leak was very obvious. Learning a lot about heating. Keen to save up a quarter of a million and get my own house to play with.
Looking like we'll get there eventually. Will need to find out how to balance radiators as fairly well all the valves have been backwards and forwards and have lost their original position.
brightspark
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pick the.radiators that are getting the hottest 1st. turn rad valve right off then slightly open . till it still heats up full then on to the next and so forth the drainplugs usualy leak when hose is put on them. there cheap and nasty with no stuffing gland causing water to come through threads
