Worth fixing or possible to fix old Marathon Myson

[spacecat]

Thanks I will investigate further and report back.

 

[boabcelt]

I think iep may be getting confused about what a gravity system is and what an open vented system is. To the OP, it sounds to me that you have pumped ch and a gravity circuit for your hot water. This was how many older systems were plumbed. It usually had 1" (28mm) pipework or larger going from tappings on the boiler which were seperate from those for the heating. The only thing controlling the temp of your water is likely to be your boiler stat. If your heating temp is satisfactory, then as suggested earlier, there may be an airlock or partial restriction in the primary pipework to the cylinder.

 

[iep]

Hi Boabcelt, I think you are quite right thanks for clarrifying.

I was referring to a gravity fed hot water system as one where the cold tank in the loft pushes the water through the HW cylinder rather than mains pressure. I did not mean a 'gravity circulation system' where (I guess) convection/gravity is used to produce flow through the HW primary pipework. Sorry if I used the wrong terms.

However, it is all speculation until spacecat gets a chance to check out his system.

Out of interest, given that a zonevalve can still be used to isolate the primary HW circuit in a gravity ciculation system (at least from the reading I have been doing), is it impossible for thermostat to be used? If the radiators are properly up to temp (about 70/75 degrees) I would have thought that the hot water would be dangerously hot without a thermostat on the cylinder. Sorry to be a bit off-topic there but keen to understand.

Cheers,

iep

 

[spacecat]

i must be honest i found the whole Y,C,S boiler systems very confusing

i must be on the older type i think.

The hot water cylinder definitely does not have a thermostat on it.

the system is also quite old- the cold tank is galvanised steel.

the pressure from the cold taps in the bathroom is quite weak compared to the mains feed in the kitchen but the hot water in the bathroom is quite a high pressure.

There is a honeywell thermostat in the hall but I have NO idea what it does as it is not visibly connected to anything. It is set at 21 C

 

[iep]

Hi Spacecat,
Without knowing a bit more about your system it's very difficult to advise further.

It's possible (I guess) though I would think unlikey that you have a sealed system where the hot water is pressurised by the incoming cold water main (rather than via the cold water tank). This would explain why you have decnet hot water pressure in the bathroom but not cold. However, given the age of the sytem this seems very unlikely to me.

Did you find any zone valves at all? Do you have a central heating header tank in the loft? The s-plan. c-plan stuff might seem confusing but you probably need to work out which you have if you are going to get an meaningful advice.

Cheers,

iep