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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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boiler pressure
my ideal isar he35 has been fine for the last 6 weeks since fitting
until this week, i noticed the pressure had dropped to 0.75 bar from the usual 1 bar (recomended when cold) i topped it back up to 1 bar and it held this until the central heating had been on again, when it had again dropped to 0.75 bar. This has continued all week it never drops below 0.75 and works o.k. i can see no apparent leaks and the pressure release valve has not discharged any water, the maximum pressure reached when running is 2 bar. The only mention in the handbook of 0.75 bar is the pressure at which the expansion tank is pre pressurised at. has anyone any ideas thanks in advance |
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"Set Square" wrote in message ... In an earlier contribution to this discussion, wrote: my ideal isar he35 has been fine for the last 6 weeks since fitting until this week, i noticed the pressure had dropped to 0.75 bar from the usual 1 bar (recomended when cold) i topped it back up to 1 bar and it held this until the central heating had been on again, when it had again dropped to 0.75 bar. This has continued all week it never drops below 0.75 and works o.k. i can see no apparent leaks and the pressure release valve has not discharged any water, the maximum pressure reached when running is 2 bar. The only mention in the handbook of 0.75 bar is the pressure at which the expansion tank is pre pressurised at. has anyone any ideas thanks in advance Stick a pot or something under your overpressure relief pipe, and see if it fills up with water. If your expansion vessel is buggered then upon firing up, the pressure will rise, the expansion vessel will not accomodate that pressure rise and the overpressure relief valve will operate ( at about 2.5 to 3 bar ) dumping water out of the 15mm pipe that presumably emerges outside your house wall somewhere. Then belatedly you look at the system pressure and find it's dropped down to 0.75 bar. That's one possibility anyway. If you keep filling up the system with mains water to repressurise it eventually all the inhibitor in your system will be flushed away and your boiler and radiators will start to corrode etc. Andy |
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wrote in message
oups.com... my ideal isar he35 has been fine for the last 6 weeks since fitting until this week, i noticed the pressure had dropped to 0.75 bar from the usual 1 bar (recomended when cold) i topped it back up to 1 bar and it held this until the central heating had been on again, when it had again dropped to 0.75 bar. This has continued all week it never drops below 0.75 and works o.k. i can see no apparent leaks and the pressure release valve has not discharged any water, the maximum pressure reached when running is 2 bar. The only mention in the handbook of 0.75 bar is the pressure at which the expansion tank is pre pressurised at. has anyone any ideas thanks in advance diaphragm in expansion vessel ? RT |
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On Sat, 11 Dec 2004 18:45:50 -0800, andrewd90 wrote:
my ideal isar he35 has been fine for the last 6 weeks since fitting until this week, i noticed the pressure had dropped to 0.75 bar from the usual 1 bar (recomended when cold) i topped it back up to 1 bar and it held this until the central heating had been on again, when it had again dropped to 0.75 bar. This has continued all week it never drops below 0.75 and works o.k. i can see no apparent leaks and the pressure release valve has not discharged any water, the maximum pressure reached when running is 2 bar. The only mention in the handbook of 0.75 bar is the pressure at which the expansion tank is pre pressurised at. has anyone any ideas See FAQ. 1.25 bar pressure rise is rather large and may indicate a partially failed (or just possibly undersized) expansion vessel. -- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at www.diyfaq.org.uk Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html |
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my ideal isar he35 has been fine for the last 6 weeks since fitting
until this week, i noticed the pressure had dropped to 0.75 bar from the usual 1 bar (recomended when cold) Probably a dodgy or undersized expansion vessel, or simply not inflated to the correct pressure before filling the system. With a pressure rise of at least 1.25 bar, you are quite likely to run into problems. Given the new installation, it could be either a manufacturing fault, installation fault (not checking charge pressure), or a design fault by the installing engineer who didn't calculate the capacity of the system and relied on the inbuilt vessel to accommodate expansion, when it was not up to the task and should have had an additional external vessel fitted. Do you have a large house by any chance? Christian. |
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Christian McArdle wrote: my ideal isar he35 has been fine for the last 6 weeks since fitting until this week, i noticed the pressure had dropped to 0.75 bar from the usual 1 bar (recomended when cold) Thanks for all the replies they have certainly given me some ideas, my house isnt particularly big more unusual 60' deep by 18' across, the boiler supplies 13 radiators + 1 towel rad. I fitted the boiler myself and was concerned at the expansion vessel section however i was assured it 'should' be o.k. my old system had 28mm flow and return pipes running to the old tank in the centre of the house 30' each i utilised these when fitting the combi boiler i intend removing them and connecting into the 22mm pipes. I think it will be best to fit an expansion vessel at the same time, just a couple of questions, can the vessel be fitted anywhere on the system,? can you recomend any particular make? would i create another problem by oversizing an expansion vessel? Whilst i am asking, when i fitted the boiler i installed trv's upstairs, when doing the above i will probably fit an automatic bypass, what is the ideal location to fit one of these thanks again |
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i intend removing them and connecting into the 22mm pipes. I think it
will be best to fit an expansion vessel at the same time, just a couple of questions, can the vessel be fitted anywhere on the system,? can you recomend any particular make? would i create another problem by oversizing an expansion vessel? Some boiler manufacturers state locations for the expansion vessel. However, as this is an additional one anyway, you can put it anywhere on the system that can't be valved off from the boiler. You can't (within reason) oversize an expansion vessel. I would probably calculate for a 0.5 bar rise, which gives loads of headroom. Christian. |
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