My wife and 3 young children are thanking me for this... I had a cold rad when I turned the heating on this season, so tried to balance the system today (I took a while to get around to the job...). I turned off all other rads, ensured this one was bled and fired up the central heating. No joy. So I thought it might be an air lock (it's in an extension, not at the end of the system, but tapped in somewhere along its length) I closed its valves, removed the bleed valve and fitted a hose to a fitting and screwed it in, then opened each valve in turn. Water ran freely from each with no audible glugging of air. I could hear the filler tank refilling in the loft. In the area around the valves the water started to warm. So I put it back to as it was and opened all the other rads, but now the boiler won't fire up. I put the thermostat up high and the programmer to on. The pump in the airing cupboard is too hot to touch and I could vageuly hear aereated water being passed. I wondered whether the 3-port valve was cooked. The little lever on it moves freely with no tension between manual and auto. I took off the head and the actual valve spindle seems jammed as it rotates less than 1/8 turn. I assume it could have been this way for some time and I hadn't noticed. I turned off the CH at the programmer and turned on the water. the children have just had a bath so there should be water to heat, but once again the bioler clicks in but won't fire up. So, I'm confused. Why will the boiler no longer fire up (I assume a safety cut-out is operating? If the above is all I've done, how did I break it? Was it putting the boiler on with all the rads closed? And why is that rad cold? A hapless DIY-er with 3 cold little ones...
I dunno. But there's some things to check (assuming you have opened all the closed rads again?) The operating sequence is: programmer turns on CH or DHW or both and sends this signal to the 3-port valve. This then moves to the appropriate position (which should be easy enough to look up on t'net, but I don't know what it is...) Once the 3-port has moved into its correct position, it trips a micro-switch which then turns on the boiler and pump. The fact the pump starts up suggests the boiler is also getting this final signal, and you are saying it does 'click'? Ok, some Qs: 1) When you turn on the CH, the DHW, both, and then offski using the programmer, does the 3-port valve go 'whirrrr' each time? Can you see a wee lever wot points to 'A' and 'B' and stuff as it does so? When you turn it on to CH do you get a 'whirrrr-click'? Ditto when you choose DHW only? 2) When you say the boiler doesn't fire up, do you mean it really, absolutely doesn't fire up at all even for a few seconds from COLD? You know the 'flow' pipe from the boiler? - it's the one which goes to the central connector of the 3-port valve - does that pipe feel hot at all? 3) Where is the pump fitted - is it on the 'flow' (before the 3-port) or on the 'return' to the boiler? (If it's on the flow, then my guess is that your 3-port valve ain't opening as it should, even tho' the valve 'head' is moving and tripping the microswitch. Your symptoms certainly suggest a boiler that is starting up for a short while and heating up the water inside, but a blockage is preventing that water from being shifted out. The very hot pump would agree with this. But that's just a guess.)
That's really useful to understand that sequence - thanks. The boiler is an old Potterton 16-22. It certainly sounds like it is clicking in and out. I've got its front thermostat set to full on. I can't check the whiriing of the 3-port valve as I'm alone right now and can't get upstairs quick enough, but I'll check it when my wife gets home. The lever is sat towards the 'auto' setting but when I move the lever there is no pressure on it at all from the motor. The pump is on the feed side. An update. I left the system for 2 hours to cool and have now just turned on semi-successfully. I guess that is normal? I then turned on the CH. At the moment, all rads are fully open, so some are hot, some are lukewarm and even my problem rad is luke warm in its top half. I've now put them back to their previous 'balanced setting' and will give it a while to balance. The boiler continues to click in and out; so things seem to have settled down. So what should I conclude? Does it suggests it's clogged and the boiler is getting starved, so overheats and shuts off? I last had a power flush and fernox treatment 2.5 yrs ago. It's mainly 1980's microbore, so it is not unreasonable to assume it is still clogged somewhat I suppose?
The spindle on a 3 port valve dosn't have much movement rotTation Someone on hear described it as having a movement on 10 past as looking at a clock.
Having your boiler on max ain't going to help... That will allow the flame to continue heating the water possibly faster than the pump can shift that very hot water away. If your boiler 'stat is clicking fairly regularly even shortly after a 'coldish' start, that suggests the water is being heated too quickly. Ideally your boiler should be 'clicking' on and off at the set thermostat level only once your whole system has heated up, and the boiler is then chust keeping it 'topped up'. So, do you think you need your boiler set at max? Do your rads chust not get hot enough if it isn't? If you can, knock it down a tad - from 5 to 4, possibly even less, for example. If the same thing happens when you're on DHW only, then it ain't a block in your microbore. I'm not surprised it happened when your started balancing your system, and shut down most of your rads... The 'boiled' water simply had nowhere to go to get cooled down.
Thanks Jitender I didn't appreciate how little they move. I read elsewhere that they only rotate by 10 degrees or so. Devil's advocate. Excellent comment, thanks for helping me. I really didn't think it through like that. I just wrongly presumed the boiler pump would also increase its flow rate, which, after a sleep from last night's stressed state, seems daft. I'm even sat here wondering if the boiler even has a pump or whether it is just the airing cupboard pump doing all the circulation... So, by a little after midnight, all the rads had come up to temperature with the TRVs or valves set to their previous 'balanced' setting. So I guess your last line might be right, that I unbalanced the system and overheated the boiler. I will now take your suggestion of reducing the boiler thermostat and see if the CH still all gets hot, because you are right - I don't think it needs to be up that high. I can then monitor how the boiler responds on just DHW only to help see if it is the microbore or not. Great suggestions from you all and you have really helped me. My thanks Mark
Sorry might be silly suggestion have you bled the pump Sounds like circulation problem water not flowing first port of call pump
Hi Albertross boy, Not in any meaningful way. By that I mean I waited until I heard the air gurgling through the pipes and the cracked open the central screw and let the water seep out for a bit. I'll read up online to check that I've done sufficient here. I would like to get all that air out of the system as it bugs me first thing in the morning when the heating starts as my bed is right next to it. Strangely though, there is no air in the rads.
when the boiler is regulating itself is the pump still running heating being called for(programmer on) room stat on boiler on but not alight is pump running if yes all working good if a radiator is cold and it shouldnt be could be air lock in pipe work turn all the other rads off (apart from cold one)using standard rad valve end not thermostatic valve(some dont turn off will let water thru) this will push air thru pipe work into rad you might have to turn central heating off and on using programmer let water settle before turning on again if air in pipe you should hear it gurgle into rad turn each rad on one at a time letting each one get hot before turning next one on balance a system rads cold all valves open turn on central heating feel which rad gets hot first turn off heating turn down normal rad valve(not trv) on that rad until its closed then open it one whole turn turn on heating check rads which rad is getting hottest first same process as first rad but undo valve tad more than previous one last rad shouldnt have to touch when heating comes on all rads should heat up toghether room temp adjusted with trv's and room stat in main living area
Thanks for laying it out so clearly for me Albatross Boy. I'll start working through it systematically like you've suggested, and I'll report back. Mark
Albertross boy, I think I must have been trying to do too much all at once. I got the cold rad working again by doing as you say but also by removing the bleed valve and fitting a hose, then undoing each rad valve in turn. I heard no glugging though but it did the job. After that, I balanced the rads incorrectly by adjusting the TRVs, so following your advice I have now done it by the other valve. Everything heats up fine now. I can't say I've fully worked out whether the pump is still running whilst the boiler switches off, so I still have a lingering doubt there. But for now I'll monitor the boiler and see if I can detect how it is operating. Thanks for all your help everyone. Case now closed. Markyboy.
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