Air in loft?

MickyP10

MickyP10

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Just replumbed the central heating system on a long bungalow through the loft because it's leaking under the floor somewhere and I'm sick of the stress trying to find the leak, ripping up the floors, etc.

Few things. Obviously there is a huge amount of air in the system thrashing around and I need to get rid but I plumbed in a couple of AAVs in the centre of the loft. Now I'm thinking maybe I should have either end and middle (loft's 22metres end-to-end). Rads at the far end aren't warming at all. I'm thinking, either massive airlock (and there is a lot of 'standing' air), the pump's not up to chucking the water up the walls and through the loft (although it was fine on speed one before; now it's on position three). Was going to add vents at either end to see if the situation improves. Can you get manual vents? AAVs always seems to leak after a while: not good in the loft.

Thanks in advance.
 
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Yep. was going to shut down the working rads to see if the non-workers came to life, then I thought if I can't get the air out, I'm not giving it a fair chance: ie, one of the room rads is 4-5 metres from the centre feed 22mm 'rail', so, methinks, it has a huge capacity for causing an airlock and buggering up the flow to the rads after this one. Do I/should I have a vent on each long branch?
 
HI

if the system is sealed then the pump should be able to get the air out.i have never had air lock in sealed systems.remember water pressure over 1 bar can easily take the air to the rads where you can release it .why do you need that many air vents ?
fit couple if you want but your system will be fine with out them.
 
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Okay, ta, maybe I'm being a bit hasty. But I can hear a lot of air thrashing around at the pump and in the drops and I wondered a) whether the huge amount of horizontal pipework could bugger up the conventional natural bleeding process (ie, if underfloor, the air naturally rises into rads and I'm bleeding the rads and not getting the air out - at least, the sloshy sounds are still there and I still have cold rads) or b) whether it was indicative of the pump not being man-enough to shoot it round. How long should it take to de-air a big filled system? Couple of days/weeks? Just thought some extra vents would speed things up. Could be wrong, though - and I am probably am...
 
1. Did you just renew the pipework
2. Are the TRV's two-way
3. Are the lockshield valves open
4. If the TRV's are old unidirectional types, have you plumbed it correctly re: flow/return
 
Hi ManxPlumber

Ta for reply.

Added wall drops and plumbed loft and new feed/return to boiler, so replaced pretty much everything.

TRVs are Danfoss but I can't find a part number. Have attached a blurry pic. Plumber who was going to do the work, then was too busy, said they were unidirectional BUT I know some aren't on the flow. Then again I have a couple of non-TRV'd towel rails in the system and they aren't getting any warmth either. Was going to try shutting some of the rads off to see if the cold ones come to life.

Building's 22 metres long and I have only fitted air vents in loft in the middle. Wondered if they should be at either end, too. There are 18 rads, and with the additional of extra wall drops, a lot of pipe so, I guess, huge potential for trapped air. If, say, one of the (new) automatic air vents didn't vent, could that do it, too? One weeps a bit of water and just wondered if it wasn't working properly. Then I wondered if I'm asking too much of the pump Grundfos 15-60 130 although, as I said previously, it used to work fine on the slow speed before.


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Just found someone else's TRV (below) which is the same as mine and shows the side I can't see. Are these unidirectional?

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How much rise did you put in the horizontal pipework to the vents
 
Am I right that if the water is seriously aeroated (ie you've just filled it from bone-dry and fired up the boiler), it won't bleed properly anyway? Therefore best to leave it for 24 hours or so. Reason is the pressure has dropped a bit (no leaks), so I'm assuming the water has de-aeroated and passed through some of the aavs. Or am I spouting rubbish?
 
Think you`re right ;) and that`s a good rise on pipes too . If it still won`t clear- consider a de.aeratore / airjec. with an aav on it :idea:
 
Thanks for that. Will try it later when I have enough Dutch courage. Have you a link to the de.aeratore you were suggesting, please? Haven't heard of them!
 
Thank you. Going to see if it's any better in a minute...
 
Got most of the air out of remaining rads by shutting down the working rads and methodically turning one on at a time, bleeding, shutting down and moving on.

Works well but to get decent heat out of the remaining 16, (after balancing), I have to turn a couple off. Pump's on 'three', tried it on two and it immediately went cooler, so I think it's running out of flow, probably because the old system under floor had 15mm flow and returns and I've installed 22mm, and with the extra wall drops, I guess it's all getting a bit much. Current pump is Grundfos 15-60 130 and I thought I could just buy a more powerful one, but a look on the company website keeps steering me towards Magnas and Alphas which, at first glance, look the same rating as I already have, albeit a different model. Does that mean I already have the most powerful domestic pump?
 
D

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