My great aunt's radiators are constantly cold, you can bleed them on one
day and the following day they need doing again.
She's had a heating engineer round today who's told her that her hot water cylinder is drawing air in and she needs a new one. The problem is he's also told her she needs a complete new system....to the tune of 15k!
The heating engineer didn't tell her this until my Dad had left... :roll: my great aunt is 101 and this has really worried her and doesn't seem to ring true to me. Surely she would only need a new cylinder? :?
Sounds a little suspicious to me too, but I cannot offer any advice without having information about what type of system it is.
Obviously, we cannot see your system so cannot simply dismiss your plumber's comments, but usually systems repeatedly filling with air are caused by bad design, and the fault has no connection with the hot water cylinder.
The system is indirect. The engineer has replaced the pump because apparently the old one (a year old) was too small, if the old pump was set at 2 or 3 and the new one is set at 1..... Would this be any different?
If the new one is set any higher, water starts coming from the overflow out of the roof.
I bled all radiators today but there was no air, just water. They were also all hot at the top but cold/warm at the bottom.
I noticed that the stop valve on the heating return (I believe) within the airing cupboard is not working as it should, the head would just keep turning. The flow was very hot but the return was cold/warm, would this be because the stop valve is stuck/jammed?
Would this also possibly be the reason for the radiators not working as they should and the hot water being hotter than normal?
If the valve is not working properly, the flow of the heating system is not working as it should, if its not flowing the way it should would the heating pipe running within the hot water cylinder get hotter than normal or flow slower therefore heating the hot water thats already within the cylinder?
Does it sound like there is a problem with the cylinder IE: A leak drawing air into the heating system like the engineer has said?
Should I just get the stop valve replaced and see where it gets us?
Also..... Would it of taken a day for two engineers to figure out a leak and not find the tap jammed?
Unfortunately, there are several different types of indirect system and without knowing which type it is, there is only so far we can go with advice.
If there is air constantly being drawn into the system, fitting a bigger pump may exacerbate the problem.
If radiators are cold at the bottom and hot at the top, this is caused by insufficient flow of hot water. So if you have a new bigger pump, and still no circulation of water, where is it going? Well, there are several options. Firstly, is all the water circulating just some of the rads and failing to reach others? Try balancing the system (See projects section on how to do this).
Secondly, and probably more likely, a bypass valve has been left fully open, or the cylinder lockshield vale is fully open. So the water is simply taking the easiest route and avoiding the heating circuit.
You need to google sundial plans (honeywell is a good site) and describe which plan is closest to your design.
As for the valve, well that's how they break. Just turn, and nothing happens. It could be shut, open or in between. Trouble is, without knowing exactly where it is in the system, it is difficult to tell what it is supposed to do. It may need adjusting, so does need to be replaced.
Symptoms of a faulty cylinder are discoloured hot water from the taps, and overflowing central heating header tank. (The tank overflow to outside not the expansion pipe) AS you have not mentioned either, I would not point the finger at a fault here. Cold rads does not indicate a cylinder fault either.
It took a day to change a pump (unnecessary?), fiddle about and come to a suspect decision? Frankly, I would be wary. As I said though, I cannot condemn anyone as I cannot see the system.
The overflow from the expansion pipe into the header tank is caused by a badly designed system. Turning the pump speed up will increase the pressure differential in the system and consequently, make the fault worse. Although this needs to be rectified, it is not causing poor flow of water around the system.
Stop valves (or rather gate valves with red handles?) found in airing cupboards have two possible functions. If the tap is at about chest height and the pipes in which they fix disappear into the loft, thy are most likely isolation valves used to shut off the different flows and should be fully open.
If the valve is lower down and fitted in the heating circuits they are most likely being used as restrictor valves and will normally only be very slightly open (or maybe even shut if it's an unrequired bypass). Opening these valves too far will unbalance the system and stop the water from flowing around the rads.
Of course another possibility with the overflow and trapped air problem, is oxygen will be drawn into the system and cause it to rust and the resulting sludge can build up and restrict flows.
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