cold bathroom rad

[John.Stitch]

Bit of a story, so are you sitting comfortably?

The Aga used to have the bathroom rad connected to it to absorb some of the excess heat from the AGA.

4 years ago I installed a separate boiler and rads for central heating and I disconnected the bathroom rad from the AGA circuit and hooked it into the boiler circuit and it worked fine.

The HW cyl was 20 gallons compared with an ideal 40 gallons.

The EH and coil went in January, so I replaced the cyl with a 35 gallon tank.

This new HW Cyl has good insulation unlike the previous one which had the four red panels strapped to it which came lose and fell to the ground.

But the water from this new HW cyl gets too hot so I reconnected the bathroom rad to the AGA circuit to act as a sink.

But the rad does not heat up so I'm trying to figure why.

The feed for the rad is tapped in the loft, about 3 feet from the expansion tank, to the expansion pipe for the AGA which in turn comes off the flow to the HW cyl.

But the expansion pipe is only just warm in the airing cupboard above the HW cyl, which makes me think that the insulation on the tank is very good and no excess hot water is produced to heat the rad.

The return for the rad is tapped at the AGA return..

The rad bleeds water with obvious pressure so apparent blockage.

If I remove some of the insulation will this cool the HW down?

 

[twgas]

All sounds a bit dodgy, you shouldn't "just connect" different systems together. I would say you need a professional eye cast over your work.

 

[John.Stitch]

The two systems are separate.

 

[twgas]

So, what heats what?

 

[John.Stitch]

The AGA heats the hot water cyl and is connected to the bathroom rad.
The boiler heats 12 rads in other rooms.

 

[jobloggs]

Is the suppy from the AGA pumped? If not and it is a gravity feed then you are depending on hot water rising in the system and you appear to have the radiator below the the point where it is tapped off in the loft.

 

[twgas]

I would suspect an airlock is preventing the rad heating.
Removing the cyinder insulation would not help - it would allow the cyl to cool slightly but the Aga would start heating it again so cost you money.

 

[John.Stitch]

Is the suppy from the AGA pumped? If not and it is a gravity feed then you are depending on hot water rising in the system and you appear to have the radiator below the the point where it is tapped off in the loft.

There is no pump on the AGA circuit and what you say is true about the tapping point for the rad in the loft.
But this layout did work well with a HW cyl of 20 galls rather than the present 35 gall cyl.

 

[John.Stitch]

I would suspect an airlock is preventing the rad heating.
Removing the cylinder insulation would not help - it would allow the cyl to cool slightly but the AGA would start heating it again so cost you money.

Thanks for the comment regarding the insulation. I will not touch it.

I will check the circuit for any air locks, I may shut the AGA down overnight and drain it is to see if that makes any difference.

The query I have is that the expansion pipe coming off the feed into the HW cyl is only just warm, which suggests that the insulation is doing its job and it is an efficient system.
Perhaps because the expansion pipe is not hot then the rad does not heat?

 

[jobloggs]

The reason the expansion pipe is not hot is nothing to do with insulation. It means that there is no flow in the pipe.