Hydronic Open-Vented Central Heating System
 

Hi

Last weekend the overflow to the expansion tank started to drip. I took a
look at the tank and manually reduced the water level in the tank. I was
expecting to find the ball-valve feed dripping and needing to be replaced -
but it wasn't.

Over the last few days the water level in the tank has risen around 1", so I
presume that water is returning via the expansion pipe. Could someone expand
on what the possible causes are?

Thanks

Hydronic Open-Vented Central Heating System
 

In an earlier contribution to this discussion,
Denny wrote:

Hi

Last weekend the overflow to the expansion tank started to drip. I
took a look at the tank and manually reduced the water level in the
tank. I was expecting to find the ball-valve feed dripping and
needing to be replaced - but it wasn't.

Over the last few days the water level in the tank has risen around
1", so I presume that water is returning via the expansion pipe.
Could someone expand on what the possible causes are?

Thanks

I assume that you have 2 tanks in your attic - a large cold water header
tank for the HW system, and a smaller fill and expansion tank for the
primary circuit? I assume that it's this smaller tank with which you have
the problem? I assume further that the water level in the large cold header
tank is higher than that in the small F&E tank?

If these assumptions are correct, I fear that you need a new hot water
cylinder. The HW cylinder has an internal coil/heat exchanger through which
water heated by the boiler passes, heating the domestic hot water without
mixing with it. BUT, if this coil springs a leak, the primary and secondary
circuits *do* mix - causing water from the higher tank to flow into the
lower tank.
--
Cheers,
Roger
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Hydronic Open-Vented Central Heating System
 

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Denny wrote:

I assume that you have 2 tanks in your attic - a large cold water header
tank for the HW system, and a smaller fill and expansion tank for the
primary circuit? I assume that it's this smaller tank with which you have
the problem? I assume further that the water level in the large cold
header tank is higher than that in the small F&E tank?

If these assumptions are correct, I fear that you need a new hot water
cylinder. The HW cylinder has an internal coil/heat exchanger through
which water heated by the boiler passes, heating the domestic hot water
without mixing with it. BUT, if this coil springs a leak, the primary and
secondary circuits *do* mix - causing water from the higher tank to flow
into the lower tank.
--
Cheers,
Roger


All your assumptions are correct - Thanks for the clear explanation Roger