Constant (small) stream of water running thru tundish.

[Pauli11]

Hi,

I have a Santon Premierplus unvented tank, about 10 years old.

The immersion heater has never worked, and Im about to get someone in to have a look at it. I noticed the problem below when I got to the tank

While I was looking around the tank, I heard water running and noticed a constant but weak flow of water (more like a dribble) running through the tundish. Its obviously been running for a considerable time, as there was a lot of white "scum" coating the tundish. It seems to be draining away via the larger drain pipe ok, but should this be happening? If not, what are the likely causes, and it it an expensive or difficult problem to rectify?

Also, how much am I likelly to pay to have the immersion heater on this unit A. fixed B. Replaced.

Many thanks

 

[Dan Robinson]

The dribble probably due to the expansion vessel failing or needing recharged.


Oh the joys of a well maintained cylinder? Didn't get its annual service I would wager? .

 

[Pauli11]

To be honest, I didnt even know these needed an annual service.

Is it a costly fix?

 

[Dan Robinson]

If it needs recharging then it is easy to do.

The immersion depends on the access and ease of draining the cylinder.

Expect 1 to 2 hours labour and materials.

New vessel costs depend on the size. Guestimate around £50 +/-

Can't remember how much the immersion are, but it might just need resetting. They are often left set too high and can over heat when they scale up.

 

[Pauli11]

Thanks for that

I checked the expansion tank, and the pressure is 2.75 bar (40 psi). This is below the 3.5 bar its supposed to be pressurised to.

Would this .75 bar pressure drop be enough to cause the water run?

 

[CBF]

you can't check it the way i bet you did, there can't be any pressure feeding it when you check it, if you didn't turn off the incoming mains & open a hot/cold tap (depending on where the EV is connected) to relieve the pressure you won't get the correct reading & yes any unvented cylinder needs a yearly check by someone that holds a G3 cert

edited: cause Dan pointed out that i'm a d1ckhead

 

[Dan Robinson]

turn off the incoming mains & open a cold tap to relieve the pressure

Tut tut .

 

[Pauli11]

Take it thats not the way to do it then?

 

[Dan Robinson]

Nope

 

[Pauli11]

Oh, erm, right. Thanks for that.

 

[Dan Robinson]

Cbf has amended his post for you.

 

[Pauli11]

Ok, I turned off the water supply, ran the hot and cold tap until water stopped. Exp tank registering only about .3 bar. I have repressurised it up to about 3 bar (old car foot pump doesnt seem to want to go any higher!) and switched the water supply on again.. Exp tank registering about 3 bar, but the drip is still there at the tundih.

Did I do the correct thing above?

 

[Pauli11]

Ok, I turned off the water supply, ran the hot and cold tap until water stopped. Exp tank registering only about .3 bar. I have repressurised it up to about 3 bar (old car foot pump doesnt seem to want to go any higher!) and switched the water supply on again.. Exp tank registering about 3 bar, but the drip is still there at the tundih.

Did I do the correct thing above?

 

[Dan Robinson]

Assuming you actually were pumping against atmosphere then yes. If it has been doing it a while though anvil's you have hard water then, chances are, one of the safety valves is shot.... time to call a G3 certified plumber.