Hi All, need a bit of help on CH problem if possible. System is a Glow-Worm Space saver 30 boiler, a Grundfos 15/50 Pump, Honeywell room Thermostat (no model number shown) and a Honeywell Sundial Y Plan Mid Pos Diverting valve (V4073A). OK ? Now then, Water heating is fine but when switching on CH the boiler fires up ok and, if starting from stone cold, runs for about 50 mins with radiators reasonably hot, or if starting from warm(ish) runs for about 20 mins. The room stat is set at 20 deg but when turning the dial the click is heard at about 15 deg so I would imagine something else is causing it to turn off. I suspect there is air in the system as I can hear occasional gurgling / whooshing (every 10 / 15 secs or so) from the vacinity of the pump. I have bled this and all the rads, with the boiler on and off, but to no avail. Have not had any air from the rads but on removing the centre screw from the pump there is a tiny amount of air coming out and, if I put my thumb over the hole, after a second or so I can feel air pressure against it. This will happen each time I put my thumb over t'hole. Have checked the F&E tank which appears to be ok with no blockage in outlet. It would appear that air is being drawn in from somewhere, but where. Incidentally, the pump was new 5 years ago so don't think that is the problem. Any help appreciated.
CH Air Problem
- Thread starter Papageno
- Start date
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Thanks for that G4Y but am convinced pump is ok as I've had it out -visually it looks new with no signs of sludge or errosion etc - put mains to it for a few moments and impeller works fine. Will search threads for blocked feed as you suggest. thanks.
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The vent is open to air but also under the same head of pressure as the tank is exerting once the system is filled.
Just because theres a tank on the feed does not mean there is more pressure from the feed than the vent...so why jump to the conclusion that air is coming in via the vent and not the tank?
Just because theres a tank on the feed does not mean there is more pressure from the feed than the vent...so why jump to the conclusion that air is coming in via the vent and not the tank?
Well Marty, you obviously think that you know more than the professionals who have made suggestions as to what may be the problem.
If that is the case then you will be well able to sort it out without any further assistance from us here!
Tony
If that is the case then you will be well able to sort it out without any further assistance from us here!
Tony
Not the case Tony!
but saying "air drawn in by vent pipe" isnt very helpful....whats the OP supposed to do based on that comment...remove his vent pipe?..its there for a reason, and by design should not be a cause for air in his system..lets wait and see what actually is the root cause.
Marty.
but saying "air drawn in by vent pipe" isnt very helpful....whats the OP supposed to do based on that comment...remove his vent pipe?..its there for a reason, and by design should not be a cause for air in his system..lets wait and see what actually is the root cause.
Marty.
Air can often be drawn in through the vent pipe as previously suggested.
Of course that would not happen in a perfect system!
However, a real system may have air in the tops of the rads which can become compressed or expanded by the action of the pump.
Micro leaks can affect the system under pump suction.
Excess resistance between the feed point and the vent can cause very serious problems.
We dont really know just how his system is configured. We cannot assume that its perfectly installed in accordance will all the best practices.
Its obviously not working properly so there must be a fault in either the design or the operation ( or both ).
Tony
Of course that would not happen in a perfect system!
However, a real system may have air in the tops of the rads which can become compressed or expanded by the action of the pump.
Micro leaks can affect the system under pump suction.
Excess resistance between the feed point and the vent can cause very serious problems.
We dont really know just how his system is configured. We cannot assume that its perfectly installed in accordance will all the best practices.
Its obviously not working properly so there must be a fault in either the design or the operation ( or both ).
Tony
Hi Guys, Thanks for your suggestions and comments. Couldn't get back to you sooner as broadband went down on Sat morning. Now then, update - No blockage in feed pipe but did notice a lot of damp scale and build up on a union on one port of the diverting valve. Decided to drain system down and replaced the 3/4 x 22mm union. On filling and firing the system up it would appear that everything is ok - well it's better than it was. The only thing I have reservations about now is the room stat, as the heating will shut down at around 17 deg and not 20 as set. If I wind the dial up to maximum (30 +) the heating will come on again and not go off untill manually switched off. I have noticed the room stat dial will still 'click' at about 17 deg. Is there a way to check the stat without buying another one.
Hey,
You can get these thermometer strips in places like B&Q for about £2...they look like the thermometers you would often have on the side of an aquarium etc (they are just a sticker).. they are accurate enough to determine if your T-stat is on the blink.
Marty.
You can get these thermometer strips in places like B&Q for about £2...they look like the thermometers you would often have on the side of an aquarium etc (they are just a sticker).. they are accurate enough to determine if your T-stat is on the blink.
Marty.
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