Hot water pouring into expansion tank

[patkelly67]

Hi all

I have just had a multi fuel boiler stove fitted to complement my existing oil central heating system. When the oil central heating is switched on within about 10 minutes hot water is pouring out of the multi fuel stove vent pipe into the expansion tank, as yet I have no seen water coming out of the overflow pipe.

A new twin coil cylinder was fitted to enable both the oil and the stove to be used.

The multi fuel stove casing gets hot when the oil central heating is on (radiator hot) so I guess the gravity feed pipe to the hot tank cylinder is venting out.

The 28mm feed pipe going into the cylinder from the multi fuel stove is fitted with a pipe stat which when hits 50 degrees C activates the circulating pump for the central heating which is on the return pipe. There is an additional 22mm pipe on the stove which acts as the feed for the central heating, so there are three pipes in total coming from the stove.

Should the vent pipe from the stove be constantly pouring with hot water when the oil heating is on?

I have been in contact with the plumber but they have not got back to me yet and would really like to know if this should be happening.

Is any additional information required?

Thanks, Patrick

 

[Mike Jackson]

It's not right. There's a problem with the pipework somewhere. Possible due to trying to combine gravity and pumped circuits.

Mike

 

[patkelly67]

Thanks Mike

I thought it was only happening when the oil was on but it's also happening when the multi fuel stove is well fired up. Does this change anything?

Patrick

 

[migoplumber]

does it happen, when only the multifuel is on and the oil is off??

shaun

 

[patkelly67]

Hi Shaun

It's happening on both. This morning I just had the oil on and this afternoon put the mult fuel stove on. The water is venting out of the multi stove gravity pipe on both occassions.

 

[migoplumber]

your plumber has definetly not connected to the correct pipes, or possibly not taken into consideration of where the circulating pump is.
It shouldnt happen like that at all.
get your plumber back.

shaun

 

[patkelly67]

Thanks Shaun, he has "promised" to come tommorrow or Thursday! I'll let you know the outcome. Once again thanks for the help.

Patrick

 

[migoplumber]

happy you feel we have helped you.
shaun

 

[patkelly67]

Plumber moved the circulating pump onto the feed and when the pump speed was reduced to 1 this solved the problem on the stove. The oil CH is working as normal. Thanks for the advice.

 

[patkelly67]

I thought this problem was fixed but it looks like it is not.

The gravity pipe from the multi fuel stove that goes into the cylinder gets hot when the oil central heating is on (over the summer I have just had hot water only from the oil system). There is pipe stat on this pipe set at 50 degrees and activates the circulating pump for for the multi fuel stove. This in turn causes a trickle of water to vent out of the oil central heating vent pipe (not the vent pipe connected to the multi fuel stove).

Over time the expansion tank fills up. I have turned the power to the multi fuel stove
circulating pump off to stop the pump activating and causing the expansion tank to fill up.

Any ideas if 1) Should the pipe into the cylinder from the multi fuel stove get so hot when the oil heating is on?

2) Why would the circulating pump from the multi fuel stove cause a trickle of water from the oil central heating vent pipe?

Thanks, Patrick