Combi boilers

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In reply to message posted by benprice:
I have a combi boiler that needs topping up alot is this a problem in the boiler or a leak in a pipe,the water loss doesn’t seem enough for a leaking pipe though [email protected]

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Any leak on a boiler is a serious condition.

You see fresh water (make up water) contains oxygen and this oxygen will shorten the life span of most heating systems including the boiler itself.

This is one of the major reasons as a Certified Boiler inspector I was against automatic feeders as make up can happen with no one knowing there is a problem.

At least with a manual feed if the water should drop to an unsafe or set level then the low water cuff off with manual reset would let you know there is a problem with the system.

I personally would monitor by watching the sight glass seeing how much water you are losing without the boiler actually firing.

This is a sure way to find out if you do have a leak (most lightly) on the return of this system.

If your water level does not drop then fire the system up and check valve packing glands or air vents or possible leaking steam traps.

Losing water is not to be taken lightly.

watching the guage glass doesn’T NECESSARLY MEAN YOU HAVE THAT MUCH WATER IN THE BOILER.IHAVE RUN ACROSS GUAGE GLASSES THAT WERE PLUGGED.MAKE SURE IT ISN’T PLUGGED BY BLOWING THE L.W.C.O.DOWN AND WATCH TO MAKE SURE THE GLASS FILLS UP TO THE PROPER LEVEL.

Combi boilers in Europe do not have Guage Glass. Combi boilers are fitted with Pressure gauge, perhaps temperature gauge as well. Low water pressure could be checked for by electrical switch or hydraulic pressure created by pump when demand made on boiler.

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In reply to message posted by DP:
Combi boilers in Europe do not have Guage Glass. Combi boilers are fitted with Pressure gauge, perhaps temperature gauge as well. Low water pressure could be checked for by electrical switch or hydraulic pressure created by pump when demand made on boiler.

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Well, here in the States the better boiler installers do install TRI cock, so They do not have to depend on a dirty glass to tell the water level, the gauge glass is just for a quick visual to allow someone to get a fast look at the systems water level.

The problem with any gauge attached to a steam system is the pig tails if made of cheap ferrous materials can be blocked with rust or corrosion.

The sight glass is just redundency in testing much like the tri cocks.
The gauges cannot be considered 100% accurate as the bourdon movement over time gives up it elasticity and checking the actual calibrations is very seldom done if ever.

Part of my BI yearly inspections is actually removing the gauges and putting on a hydrostatic test using highly accurate gauges depending of pressure ratings with a hydraulic pump which I can adjust for all kinds of pressures from manometer reading of inches of water to 10,000 PSIA

Most blokes here install gauges and forget about them and have no clue how to check the actual calibrations and adjust same

» This message has been edited by SylvanLMP on 11 March 2002

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In reply to message posted by Roy:
watching the guage glass doesn’T NECESSARLY MEAN YOU HAVE THAT MUCH WATER IN THE BOILER.IHAVE RUN ACROSS GUAGE GLASSES THAT WERE PLUGGED.MAKE SURE IT ISN’T PLUGGED BY BLOWING THE L.W.C.O.DOWN AND WATCH TO MAKE SURE THE GLASS FILLS UP TO THE PROPER LEVEL.

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Well, actually there is a little bleeder used to check the sight glass and it is also used to as a blow out/down to help clean the glass without disassembly in some cases, so the low water cut off does not have to come into play.

By checking the sight glass instead of the LWCO your dealing with a much smaller amount of water and THUS easier to find out if there is a problem.

The sight glass test is fool proof and lets the tester know right away if the system is dirty or is filling properly.

The sight glass is just another tool used to take a fast visual of the system and a very easy place to start your testing of the operations of the boiler.