The central heating system in our bungalow is non-sealed and powered by a 25 year old (I believe) Baxi 50?R(or B)S boiler. Probably the original fitment when the bungalow was built in 1980. The indecision about the type is because the printing has partly worn off the label. Circulation of the heating water is via a (recently new) Grundfos UPS 15-60 pump.
Both the central heating and the hot water function O.K., except in the kitchen where the hot water has a mind of its own about when it should flow, generally not flowing when the heating has been off for a couple of hours or so. It is O.K. at all other hot taps. The tap in the kitchen is one those pseudo French-style ones which stands about 9" above the worktop level, and is therefore higher than the top of the hot water tank which is mounted at floor level. Nevertheless I believe the hot water should still flow, even though the pipework to the tap is a bit 'tortuous', because the cold tanks are roof mounted giving an effective head of about 6 to 8 ft.
Also the boiler is "noisy", making those, what sound to be, "air in the system" noises, but I think this may be an entirely different problem.
The system has been bled and a recommended (by our local plumber) jollop added to the it. As previously stated there is absolutely no problem with the heating.
What puzzles me is the existence of a pipe which appears to start at the bottom of the hot water tank, goes up into the roof, and terminates at a point about 9-12" below the level in the "top-up" tank. At the top of this pipe is a brass 'gismo' about 1.5" diameter by 2.5" high with a Schrader type valve at the top of it. I say "Schrader type" because it's diameter is very slightly larger than that of a tyre valve. I know because I can't get a car tyre pressure gauge on it. The only logical explanation I can surmise for the existence of this valve is to introduce a level of positive pressure into the hot water system to compensate for the comparative lack of head in a bungalow. If I am right, what pressure should there be, how should this pressure be introduced to the system and how should it be checked? There is no "U" bend anywhere to introduce mains water, and no gauge on the boiler. If I am totally wrong, what is the function of this 'gismo'?
Thanks in advance for any help.
Tony Norton
Both the central heating and the hot water function O.K., except in the kitchen where the hot water has a mind of its own about when it should flow, generally not flowing when the heating has been off for a couple of hours or so. It is O.K. at all other hot taps. The tap in the kitchen is one those pseudo French-style ones which stands about 9" above the worktop level, and is therefore higher than the top of the hot water tank which is mounted at floor level. Nevertheless I believe the hot water should still flow, even though the pipework to the tap is a bit 'tortuous', because the cold tanks are roof mounted giving an effective head of about 6 to 8 ft.
Also the boiler is "noisy", making those, what sound to be, "air in the system" noises, but I think this may be an entirely different problem.
The system has been bled and a recommended (by our local plumber) jollop added to the it. As previously stated there is absolutely no problem with the heating.
What puzzles me is the existence of a pipe which appears to start at the bottom of the hot water tank, goes up into the roof, and terminates at a point about 9-12" below the level in the "top-up" tank. At the top of this pipe is a brass 'gismo' about 1.5" diameter by 2.5" high with a Schrader type valve at the top of it. I say "Schrader type" because it's diameter is very slightly larger than that of a tyre valve. I know because I can't get a car tyre pressure gauge on it. The only logical explanation I can surmise for the existence of this valve is to introduce a level of positive pressure into the hot water system to compensate for the comparative lack of head in a bungalow. If I am right, what pressure should there be, how should this pressure be introduced to the system and how should it be checked? There is no "U" bend anywhere to introduce mains water, and no gauge on the boiler. If I am totally wrong, what is the function of this 'gismo'?
Thanks in advance for any help.
Tony Norton