Boiler issues

Tomgunn:

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Tomgunn:

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I was called to a gas boiler today. The home owner's parents are house siting and don't want the pipes to freeze up. The gas boiler was not working and the parents though that the house had an electrical fault. When I arrived I saw that the pressure gauge on the boiler was indicating low. Not being familiar with the make and model I could not find a filling loop. I went to the local plumbing shop and was told that I could not touch the boiler as I was not a Gas Safe registered person. I explained the position and said that I was only touching the plumbing and not the gas. Anyway, after talking to the maker's tech. dept. bloke I was told hoe to re-pressurise the system. It involves a silly plastic key system situated under the boiler.


Do I really have to be Gas Safe registered to re-pressurise an unvented boiler? It is only like pumping up a car tyre. And yes, I do know not to over pressurise the system as the pressure increases with temperature.


Z.

Hello Zoom,


It's a horrible way to top up the water, in that boiler!! I have done this several times and you need to force a plastic tool, under the boiler, and it has always spilt some water out, when I've done this.


You don't need to be a gas-safe engineer to do this as it's not within the boiler!


Furthermore... you'll need to find why the pressure has dropped! Check all the valves, on the radiators'. 


The inside of the boiler has a 'bladder' that expands, and contracts, etc... hope it isn't that!


Good luck! 


Tom

 

According to the makers, occasional  re-pressurisation will be required even if the system is good.

My guess is that the key system is to prevent contamination of the drinking water in case of backflow of water into the mains water supply. When the key is withdrawn, as required after use, the boiler system can not contaminate the mains water supply if the mains pressure falls.


Z.

The pressure, of the mains water. wouldn't allow contamination plus fitting 'non-return' valves would ensure that this never happens!


 

If the mains' water pressure failed, due to a fault, then contaminated water could be drawn back into  mains water pipes only to reappear in drinking water later on. This could cause illness.


I once had to install an electrical shower in a mortuary, for certain people whose custom it was to wash their loved ones' bodies before burial.  We fitted a non return valve in the water supply because the shower hose was very long and could be dropped onto the floor where it could pick up all sorts of germs.


I believe that is why shower manufacturers have the hose restricting trays on domestic showers, to limit the reach of the shower head and not to allow it to fall into the shower tray. Again to prevent back flow of contaminated water into the water supply pipes in case of  a pumping failure.


Where the water supply is taken from a rising main, the feed to the shower must include a non-return valve to prevent any water flowing back into the mains under fault condition - it is also a good idea to include an isolating valve just before the shower unit so that it can be isolated if necessary.


Z.

Tomgunn:

Zoomup:

Tomgunn:

Zoomup:

I was called to a gas boiler today. The home owner's parents are house siting and don't want the pipes to freeze up. The gas boiler was not working and the parents though that the house had an electrical fault. When I arrived I saw that the pressure gauge on the boiler was indicating low. Not being familiar with the make and model I could not find a filling loop. I went to the local plumbing shop and was told that I could not touch the boiler as I was not a Gas Safe registered person. I explained the position and said that I was only touching the plumbing and not the gas. Anyway, after talking to the maker's tech. dept. bloke I was told hoe to re-pressurise the system. It involves a silly plastic key system situated under the boiler.


Do I really have to be Gas Safe registered to re-pressurise an unvented boiler? It is only like pumping up a car tyre. And yes, I do know not to over pressurise the system as the pressure increases with temperature.


Z.

Hello Zoom,


It's a horrible way to top up the water, in that boiler!! I have done this several times and you need to force a plastic tool, under the boiler, and it has always spilt some water out, when I've done this.


You don't need to be a gas-safe engineer to do this as it's not within the boiler!


Furthermore... you'll need to find why the pressure has dropped! Check all the valves, on the radiators'. 


The inside of the boiler has a 'bladder' that expands, and contracts, etc... hope it isn't that!


Good luck! 


Tom

 

According to the makers, occasional  re-pressurisation will be required even if the system is good.

My guess is that the key system is to prevent contamination of the drinking water in case of backflow of water into the mains water supply. When the key is withdrawn, as required after use, the boiler system can not contaminate the mains water supply if the mains pressure falls.


Z.

The pressure, of the mains water. wouldn't allow contamination plus fitting 'non-return' valves would ensure that this never happens!


 

If the mains' water pressure failed, due to a fault, then contaminated water could be drawn back into  mains water pipes only to reappear in drinking water later on. This could cause illness.


I once had to install an electrical shower in a mortuary, for certain people whose custom it was to wash their loved ones' bodies before burial.  We fitted a non return valve in the water supply because the shower hose was very long and could be dropped onto the floor where it could pick up all sorts of germs.


I believe that is why shower manufacturers have the hose restricting trays on domestic showers, to limit the reach of the shower head and not to allow it to fall into the shower tray. Again to prevent back flow of contaminated water into the water supply pipes in case of  a pumping failure.


Where the water supply is taken from a rising main, the feed to the shower must include a non-return valve to prevent any water flowing back into the mains under fault condition - it is also a good idea to include an isolating valve just before the shower unit so that it can be isolated if necessary.


Z.