Have installed a combi in a loft area. The hot water pressure to all taps is acceptable. The only trouble is filling the heating system!! Not enough pressure to fill to the required 1 bar. Any help will be greatly received???
Not enough pressure!!!
- Thread starter Registered Gas Man
- Start date
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Do you NEED 1 bar?
What is the vertical distance between the lowest and the highest point of the system?
Would it be more than 22 feet? If not, then 0.7 bar would do it. You need to set the air pressure to this and then set the system pressure to just over this.
But even so, this does not add up. I assume the boiler is at the highest point (or nearly so) and you are able to get water up to the boiler. Are you saying the mains pressure is only less than 1 bar? If you can get water up to the boiler, you can fill the system. Just don't get hung up on 1 bar.
What is the vertical distance between the lowest and the highest point of the system?
Would it be more than 22 feet? If not, then 0.7 bar would do it. You need to set the air pressure to this and then set the system pressure to just over this.
But even so, this does not add up. I assume the boiler is at the highest point (or nearly so) and you are able to get water up to the boiler. Are you saying the mains pressure is only less than 1 bar? If you can get water up to the boiler, you can fill the system. Just don't get hung up on 1 bar.
Yeah the boiler is at the highest point, and I have got water to the boiler as the hot water circuit is up and running! But the heating sytem will not budge off 0 bar on the pressure gauge???!!!
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Agreed. But the boiler wont operate heating until it has 1 bar, which it wont do, so it cant be reaching desired pressure!!! Can I make this a water authority problem? 
Water carriers now only gtee 0,7bar at the communicaion pipe! Great innit, like Transco's 14mbar.
Not very tempting to get up there with a shower pump and a bucket of water, is it!
The Sentinel thing for pumping inhibitors in (looks like a garden spray vessel) is presumably capable of connecting and getting some sort of pressure. About £70 I think - at least it would save you money on other jobs.
A powerflusher produces a fair pressure too - got one? Easy to connect at least.
Or you could hire a pressure tester for not much - Monument one pumps up to 50 bar I think! Just about to buy one in fact - does the testing job right and looks dead impressive.
Or go in the middle of the night when the pressure's higher?
Not very tempting to get up there with a shower pump and a bucket of water, is it!
The Sentinel thing for pumping inhibitors in (looks like a garden spray vessel) is presumably capable of connecting and getting some sort of pressure. About £70 I think - at least it would save you money on other jobs.
A powerflusher produces a fair pressure too - got one? Easy to connect at least.
Or you could hire a pressure tester for not much - Monument one pumps up to 50 bar I think! Just about to buy one in fact - does the testing job right and looks dead impressive.
Or go in the middle of the night when the pressure's higher?
My Kamco pressure washer produces around 1.5 bar.
You can buy a radiator bleed valve adaptor set from them for around £20 and I use a standatd garden sprayer to push inhibitor into radiators. Much easier than via expansion tank. Other benefit is Kamco are doing a filling loop adaptor so it can go straight in there.
This sounds a pretty poor mismatch between boiler manufacturers and water suppliers that they have the pressure differential in favour of appliances not working. I wonder if the new pressure guaranteed is because of the demands on the supply infrastructure caused by the trend to do away with stored water in properties.
I hadn't understood 'til now that gas combis need this min pressure to work. Is it the case for all gas combis? Since most properties are two storey, and, if you don't have the boiler in the loft, you then need only 0.5 bar system pressure, is there a way to use 0.5 bar as the min pressure? And would any manufacturer care to say why they picked 1 bar?
You can buy a radiator bleed valve adaptor set from them for around £20 and I use a standatd garden sprayer to push inhibitor into radiators. Much easier than via expansion tank. Other benefit is Kamco are doing a filling loop adaptor so it can go straight in there.
This sounds a pretty poor mismatch between boiler manufacturers and water suppliers that they have the pressure differential in favour of appliances not working. I wonder if the new pressure guaranteed is because of the demands on the supply infrastructure caused by the trend to do away with stored water in properties.
I hadn't understood 'til now that gas combis need this min pressure to work. Is it the case for all gas combis? Since most properties are two storey, and, if you don't have the boiler in the loft, you then need only 0.5 bar system pressure, is there a way to use 0.5 bar as the min pressure? And would any manufacturer care to say why they picked 1 bar?
sorry but did you mean that the mains water into the house is not powerful enough to pressurize your combi to 1 bar
If this is the case then then pressure on the mains water into the boiler uis totally inadequate and a combination boiler should not have been installed
if I am reading wrong i apologise but sheesh sounds dodgy what pressure did you get when you carried out the prelimanry checks mate?
most combi s doe have a low pressure switch oilman
If this is the case then then pressure on the mains water into the boiler uis totally inadequate and a combination boiler should not have been installed
if I am reading wrong i apologise but sheesh sounds dodgy what pressure did you get when you carried out the prelimanry checks mate?
most combi s doe have a low pressure switch oilman
Thanks guys for your help Although it was me being a muppet, Oilman was correct in his first reply. The pressure gauge is knackered. The preliminary checks where fine as as I said the hot water pressure is satisfactory. It was a long day and I misinterpreted the dianostic light to mean low pressure, ( you know what they say about overfamiliarty )and the combo of the busted gauge and my stupidity caused me to fall on the conclusion that the pressure was inadequate. Went back to the job this morning fresh head, and it was easy. But this has reslted in my finding a decent sight and enough know how to crack my next problem
Although it was me being a muppet, Oilman was correct in his first reply. The pressure gauge is knackered. The preliminary checks where fine as as I said the hot water pressure is satisfactory. It was a long day and I misinterpreted the dianostic light to mean low pressure, ( you know what they say about overfamiliarty )and the combo of the busted gauge and my stupidity caused me to fall on the conclusion that the pressure was inadequate. Went back to the job this morning fresh head, and it was easy. But this has reslted in my finding a decent sight and enough know how to crack my next problem DIYnot Local
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