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Chat Area => General Discussion Area => Topic started by: feeutfo on 12 December 2012, 17:47:12

Title: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 17:47:12
had the plumber round today, with a thermal imaging camera, inconclusive. hot spots present on all the joins, but the join that was repaired had no lagging, and the signature is the same on the repaired joint when compared to all the existing ones.

Our heating pipes are under the concrete floor as you may have seen elsewhere on here, and we still seem to have a leak. We're loosing about 0.3bar a day on the heating system. although the system was opened and drained down completely, so it could just be settling in. it did seem to settle at 0,8 bar over the last couple of day, except the las time i checked the heating was on flat out.

so question is, how much would the heating in the system increase the pressure from cold?

we have a press pack on the central heating, instead of a stop cock and tank, this allows us to measure the mains fead pressure in the central heating, and see if the pressure drops in the system, indicating a leak. i'm also trying to allow for expansion as the heating chimes in, but there doesnt seem to be any. should there be? and if so how much?

we'll continue to monitor the pressure daily. i've almost worn the loft ladder out ;D
Title: Re: thermal expansion (plumbing)
Post by: redelitev6 on 12 December 2012, 18:03:33
Might be worth checking the pressure relief valve , they can sometimes weep if a speck of dirt gets trapped in the sealing faces
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 18:12:33
Might be worth checking the pressure relief valve , they can sometimes weep if a speck of dirt gets trapped in the sealing faces

yes the plumber was hoping/praying that might be the case, sadly not that lucky, over flow is dry as a bone.
Title: Re: thermal expansion (plumbing)
Post by: Shackeng on 12 December 2012, 18:26:35
This any use Chris: http://inspectapedia.com/plumbing/Hot_Water_Expansion.htm
Title: Re: thermal expansion (plumbing)
Post by: Kevin Wood on 12 December 2012, 18:30:48
Depends how large the system is relative to the size of the pressure vessel really.

Try it. Fill it to 1 bar stone cold, then fire up the heating to maximum temperature with all radiators on. Once the boiler has cut out, check the pressure rise. I'd say 0.5 BAR more, maybe more.
Title: Re: thermal expansion (plumbing)
Post by: Marks DTM Calib on 12 December 2012, 18:31:02
Its the expansion vessel OK and large enough?
Title: Re: thermal expansion (plumbing)
Post by: Kevin Wood on 12 December 2012, 18:35:32
Might be time for the Radweld soon. :-X
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 18:37:44
This any use Chris: http://inspectapedia.com/plumbing/Hot_Water_Expansion.htm
ooh good lord, a quick glance and i'll need some to digest that.

thanks Shak :y
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 18:39:40
Depends how large the system is relative to the size of the pressure vessel really.

Try it. Fill it to 1 bar stone cold, then fire up the heating to maximum temperature with all radiators on. Once the boiler has cut out, check the pressure rise. I'd say 0.5 BAR more, maybe more.
yes its nowhere near that much, 0.1 maybe, but as the heating is in use its hard to measure, its on 24/7 atm
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 18:41:00
Its the expansion vessel OK and large enough?
looks almost new, no leaks, takes the expansion from zero to 1.5 bar with no problems afaict
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 18:43:13
Might be time for the Radweld soon. :-X

it might work now, as the main leak has been fixed. it was loosing all pressure over 24 hours, previously.

except the system is now sealed. although i do have a pot of said mischief in the garage. :-X
Title: Re: thermal expansion (plumbing)
Post by: TheBoy on 12 December 2012, 18:54:14
Depends how large the system is relative to the size of the pressure vessel really.

Try it. Fill it to 1 bar stone cold, then fire up the heating to maximum temperature with all radiators on. Once the boiler has cut out, check the pressure rise. I'd say 0.5 BAR more, maybe more.
yes its nowhere near that much, 0.1 maybe, but as the heating is in use its hard to measure, its on 24/7 atm
Easy fixed. Dig out her coat, then turn the switch off :P
Title: Re: thermal expansion (plumbing)
Post by: Marks DTM Calib on 12 December 2012, 18:59:09
Its the expansion vessel OK and large enough?
looks almost new, no leaks, takes the expansion from zero to 1.5 bar with no problems afaict

Do you know what size it is and have you checked the air pressure on it?
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 19:15:38
Its the expansion vessel OK and large enough?
looks almost new, no leaks, takes the expansion from zero to 1.5 bar with no problems afaict

Do you know what size it is and have you checked the air pressure on it?
give me 5 mins
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 19:27:34
its at 20psi

no obvious indication of size on the label, but its almost the exact same size as a pressure cooker, maybe slightly bigger. 1foot x1foot minimum
Title: Re: thermal expansion (plumbing)
Post by: aaronjb on 12 December 2012, 19:27:48
Its the expansion vessel OK and large enough?
looks almost new, no leaks, takes the expansion from zero to 1.5 bar with no problems afaict

Do you know what size it is and have you checked the air pressure on it?
give me 5 mins

ISTR you have to check the air pressure with no water in the system.. so that one might be a bit hard in 5 mins..

Unless that's why you've been gone longer than 5 mins ;)
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 19:35:10
i think hes checking there is room for the water to expand into, there needs to an air gap it it will lock.
Title: Re: thermal expansion (plumbing)
Post by: Marks DTM Calib on 12 December 2012, 19:43:41
Checking that and its volume, is it a cylinder or flat compact one? (Suspect cylinder given its a retro fit)
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 19:46:12
Checking that and its volume, is it a cylinder or flat compact one? (Suspect cylinder given its a retro fit)
cylinder
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 20:03:49
looking at google, cylinder seems to be about 8 litres, which is about right. visually anyway.
Title: Re: thermal expansion (plumbing)
Post by: paul.77 on 12 December 2012, 20:42:31
maximum I would expect of 0.5 bar rise from cold when heating is turned on. If no signs visable signs of leaks or complaints  from neighbours below. It could be leaking internaly through the condensating heat exhchanger, To check this the boiler has to be cold,,left off for about an hour.You can check the expansion vessel at the same time
what are the last 4 numbers of the boiler serial number?
paul
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 20:53:48
3544, but its only a year old.
Title: Re: thermal expansion (plumbing)
Post by: paul.77 on 12 December 2012, 21:02:41
if its a year old it may be under guarantee.
the last 4 numbers on the small silver sticker on the drop down flap.
is it the biasi m96 24
Title: Re: thermal expansion (plumbing)
Post by: feeutfo on 12 December 2012, 21:05:24
it will be under warrenty of 5 years

iirc no drop down flap, its a worcester condensing boiler
Title: Re: thermal expansion (plumbing)
Post by: paul.77 on 12 December 2012, 21:52:12
sorry getting consfused with another post.  ::)
if the boiler is turned off and is cold, there should be no water flowing down the  condensate pipe if there is then it may be a problem with the condenser unit. With the boiler cold and empty the expansion vessel should have a pressure of 0.75 bar average,for larger systems I would put 1 bar in.