Rads/hot water keeps going off??

[Freezing2]

Hi, I wonder if anyone can help me with a problem I have had for the last month or so.

I have an oil (Kero) central heating system which keeps going cold for both hot water and radiators.

I have a mid position valve, 3 speed pump and a vertical tube with vent on the end at the back of pump/valve......I need to keep releasing air from this tube/vent.......I slackened the screw on the pump and it was gurgling air out for 15/20 minutes.

It seems full of air to me but why and what's needs to be done to cure it.....I'm quite handy with the spanners e.t.c. but no idea how my central heating system works so will be grateful of any help sorting this problem.

Many thanks in advance.

Phil

 

[Best]

Hello Phil and welcome. Firstly, is your heating system fed with a little expansion tank? Not to be confused with a large cold water tank, if you had one.
It is possible to have systems working incorrectly and absorbing air.

 

[Freezing2]

Hello Best and thank you for the welcome.

Yes I have a small black plastic tank that I think is for the central heating system, the pipe from it enters the system via a T just below the pump. This tank is full of water and the ball cock is operating.

 

[Stu Davis]

You should have an open vent pipe that loops over the top of the black header tank, if you do where does that connect into the system ??

 

[Freezing2]

Yes got open vent pipe looping over header tank
This loop is connected to the outlet in the bottom of the tank

 

[PhoenixServices]

I presume in real life the outlet (cold feed) from the header tank and the pipe that bends over your header tank (vent) arnt joined except to the flow by the pump.

 

[Freezing2]

When I slacken the large screw in the centre of the pump the impellor slows and then stops completely.....is this normal?

Thanks

 

[Freezing2]

I presume in real life the outlet (cold feed) from the header tank and the pipe that bends over your header tank (vent) arnt joined except to the flow by the pump.

Not sure what you mean

 

[ShaunCorbs]

When I slacken the large screw in the centre of the pump the impellor slows and then stops completely.....is this normal?

Thanks

no should keep spinning and you shouldnt be able to stop it

 

[Freezing2]

no should keep spinning and you shouldnt be able to stop it

Definitely slows down then stops within a few seconds of slackening screw.........what could this mean?

Everything works fine if I keep bleeding the air off twice a day, but if for any reason I forget it stops :crazy:

 

[ShaunCorbs]

Definitely slows down then stops within a few seconds of slackening screw.........what could this mean?

Everything works fine if I keep bleeding the air off twice a day, but if for any reason I forget it stops :crazy:

New pump time if stops

 

[Stu Davis]

Ideally you should have a seperate feed from the tank and open vent, as it flows to the pump its the open vent first then the cold feed so in theory when the pump starts it draws on the cold feed and not the vent sucking in air.
You could hold a cup of water with the vent pipe in and when switching on the pump see if it sticks in, a lot of systems where the feed and vent are wrong suck air in on initial start up.
The pump sounds like it needs replacing and if all else fails try some inhibitor incase its system gas.

 

[Freezing2]

Ok thank you for the replys the system has worked fine for last 15 years so I wonder if it's just a case of the pump being dead inside.

As I said earlier when I release the screw the pump rapidly slows and then stops completely, when tighten the screw back up it starts again afetr a minute or so.

Many thanks