Sorry if i sound really think, but i tried to sort the boiler out last night, by raising the pressure bar, to 1.5, which i was told it needs to be at. I remember my husband doing it (well i thought i did) and copied the turning of the valve, but didnt hear any noise which i thought there normally was. Anyway the heating systen worked fine, but when i checked the bar tonight, it has risen to 2.5. I am scared to use the heating as i am wondering why the bar has risen so much??? any help greatly appreciated
combi boiler probs..............
- Thread starter ferboz
- Start date
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Was the heating system cold when you set the pressure? The valve should be opened SLOWLY to avoid the pressure getting too high too quickly. There is a pressure relief valve on the system which will blow at 3 bar so you can run the system.
If the water was cold when you set the pressure, then it is normal for it to rise when it gets hot so generally you will be ok running the heating. I would question your advice about the pressure though. With the water cold, and providing the air in the expansion vessel was set correctly at 0.5 bar (very often it is set too high) for a 2 stoey house and 1 bar for a 3 storey house, the water pressure is set at .07 bar or 1.2 bar respectively when cold. Any higher strains the expansion vessel unnecessarily.
Please post reply if you need more info
If the water was cold when you set the pressure, then it is normal for it to rise when it gets hot so generally you will be ok running the heating. I would question your advice about the pressure though. With the water cold, and providing the air in the expansion vessel was set correctly at 0.5 bar (very often it is set too high) for a 2 stoey house and 1 bar for a 3 storey house, the water pressure is set at .07 bar or 1.2 bar respectively when cold. Any higher strains the expansion vessel unnecessarily.
Please post reply if you need more info
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B
breezer
there is a smell checker button too, (but it can't spot that one)
thanx oilman, yes the system was cold when i released the valve, so i guess i am the root of the problem! i read in another thread that i could bleed the radiator to get the pressure down. However i am a bit worried about doing this also. As u can tell i am a right technophobe, when it comes to anything electrical! It is interesting tho, when u mention the 0.7 bar, as my engineer, 3 years ago said that usually this system (saunier duval) combi is kept at 1.5 bar. I live in a 2 bed bungalow, so maybe i should get this checked out??? Oh & 1 more thing......if i use the system will the pressure gauge go up anymore, thats my main worry!
You're not the root of the problem. You set the pressure when it was cold, that was correct. The root, if any, was your information about the 1.5 bar might not have been complete. It may be 1.5 bar when it's hot, but if you go back to your schooldays and the barometer, the mercury is held up by the air pressure at around 30 inches (see Thursday evening weather forecast on BBC local news). If you use water instead of mercury the atmosphere can hold up 34 feet (approx) and this is 1 bar.
Not so bad so far?
The pressure you need in your system is just enough to push the water up to the highest point of the system. In your case this is probably no more than 12 feet (about 0.3 bar). This is the AIR PRESSURE in the expansion vessel (don't worry about checking this yet - you can do that when you feel more comfortable about it
).
The next part of the operation is to set the water pressure (which you know how to do ). This is set slightly above the air pressure, in your case at 0.5 bar. It then rises when the system warms up.
The pressure may rise, but if the system is hot when the pressure is 2.5 bar then it wont rise much more if at all. Even if it does there is a safety valve to stop it going above 3 bar.
Now we get to the controversial bit. I service oil boilers, and when I service a combi, I always release the system pressure by twisting the knob on the Pressure relief valve. So you could reduce the pressure by doing this. Other operators argue against doing this for fear of dirt from the system getting under the valve seat and causing a leak (see //www.diynot.com/forums/viewtopic.php?t=3353&sid=afa2ba0a749a2d142493cffcb9aad470
Don't worry about 2.5 bar but get it set correctly sometime.
Not so bad so far?
The pressure you need in your system is just enough to push the water up to the highest point of the system. In your case this is probably no more than 12 feet (about 0.3 bar). This is the AIR PRESSURE in the expansion vessel (don't worry about checking this yet - you can do that when you feel more comfortable about it
).The next part of the operation is to set the water pressure (which you know how to do
). This is set slightly above the air pressure, in your case at 0.5 bar. It then rises when the system warms up.The pressure may rise, but if the system is hot when the pressure is 2.5 bar then it wont rise much more if at all. Even if it does there is a safety valve to stop it going above 3 bar.
Now we get to the controversial bit. I service oil boilers, and when I service a combi, I always release the system pressure by twisting the knob on the Pressure relief valve. So you could reduce the pressure by doing this. Other operators argue against doing this for fear of dirt from the system getting under the valve seat and causing a leak (see //www.diynot.com/forums/viewtopic.php?t=3353&sid=afa2ba0a749a2d142493cffcb9aad470
Don't worry about 2.5 bar but get it set correctly sometime.
phew! thanx for that again oilman! i started to seriously think i was gonna have a blown up boiler on my hands! I am in the british gas servicing scheme, although i have no date as to when they will appear as they forgot about me last year! i am relieved that i havent done that much wrong, just a bit mis-informed by the looks of it. Anyway will now be able to put on the system, with no worries ( ok maybe just a little!) Will mention to the servicer, if he ever turns up, to sort out the bar, which he hopefully will do.
thanx again for all the help.
thanx again for all the help.
If you're in the BG scheme do they come out for things such as this? at your request for no extra payment? If so get them out esp. as they seemed to have missed you out, but I presume they haven't forgotten to take your money!!!!
B
breezer
if you have BG 3 star service things like that are (should be) covered, and remind them they missed you last year, although a little bird tells me that (missing a service is quite often "normal")
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