Faulty float valve, or faulty immersion stat?

[kevin plumber]

Just inspected a hot water cylinder with a combined water tank, on inspection i found the water tank to have the float valve (part 1 type) submerged in water. The water is coming out of the overflow and i'm drawn to either of the two conclusions:

1. Ball valve is faulty and needs replacing.
2. Thermostat is bust and causing expanding water to pump over, hence the extra water in the tank being sent out of the overflow.

A second opinion would be good, cheers.

 

[Simon F]

1- turn the cold feed of, if it stops over flowing then the valve is the problem,
you don't want a type 1 valve anyway.
2 -what temperature is the water at? wont expand much from 60 degrees until it turns to steam.

what level is the float at when the cylinder is cold?

 

[mountainman]

Think about it.
If the immersion stat was overheating, would the cwst overflowing be the most obvious result??

 

[kevin plumber]

The float valve is shut off and the water isn't constantly discharging, however the water level is a few mm under the overflow. The float is submurged in water but seems to be shut down.

On arrival the cylinder was cold and the float was fully extended, as in its last point of its cycle if you know what i mean.

I would have thought if the thermostat had failed, the water would expand and pump over?

Either that or the float valve is faulty and letting by?

Thanks for the reply, just needed a second opinion, worst case i will change both if need be!

 

[kevin plumber]

Well mountain man that is the question i'm asking, at the time i inspected the tank it was cold and will return when the tank is hot to see for myself, but was just asking for a second opinion, not a sarky comment tbh!

 

[Dannypipe]

Has the float on the valve got a hole in it?

I've seen them with a small hole in the middle. From the friction of gliding across the water for years I guess. Then the float sinks and thus won't float up to close the valve off.

A 90p new orange ball and you could be back in action.

Test the stat with a meter and then you'll know, but it's not likely to be the stat is it?

Its not hard to tell if a float valve is letting by either.

 

[dontknowitall]

Suck some water out of the cistern. Push down valve to ensure water's coming out. Pull up to ensure it stops dripping. If fine, then ball float. If not fine, then you've probably found your problem.

Compare the plumber dot com

simples!!!

hehe

 

[scotty plumber]

Could the float have water trapped in it causing the valve to sink? Also is the air-trap big enough ( Distance between water level and overflow to allow for expansion? Thermostat should have a safety cut-out to prevent overheating.

 

[Dannypipe]

Yeah, I've just re-read the opening post.

Sounds like the ball valve needs a new washer.

They get indented over time. This means they over fill before they shut off.

Some people just bend the brass arm over to get over this. I personally service the valve and change the washer (takes ten minutes tops).

Or just fit a new valve, fiver from Screw Fix.

 

[kevin plumber]

Hi scotty ive looked at hte air gap which would be between the ball valve and overflow and that is sufficient. Presently with the float submerged, the water level is only mm from the over flow.

I understand that the thermostat 'should' have a thermal cut out, however i did come across one the other day which did not. The water continued to heat and was scolding when coming from the taps!

 

[Dannypipe]

So check the stat with a meter, and then you can discount it if it's not faulty.

 

[tamz]

If it was the stat the water in the cistern would be boiling hot and the place like a sauna.
Fit a 5p washer and it is sorted.

 

[mountainman]

Not a sarky comment Kevin, Tamz has answered your question.
I just thought figuring the answer out for yourself might be more gratifying.

 

[REDSAW]

i was taught to start from basics.

turn the cold feed of then run the hot tap to drain the cwst.

then inspect what your looking at.

 

[kay-jay]

5p washer tamz? i'd have thought a scotsman would advise a valve swap to get a little for the weigh in.....:wink_smile:

 

[Howsie]

With Tamz on this.

Water expands by 4% when heated. 1600% when it turns to steam.

 

[Danv44444]

Fit a new Ball valve and ball, and fit a new stat. It would cost you no more than £20 and it will be sorted no problem.

 

[mountainman]

Fit a new Ball valve and ball, and fit a new stat. It would cost you no more than £20 and it will be sorted no problem.

That will solve the problem for sure but will provide no diagnosis of the true cause.

 

[Danv44444]

For the sake of probably less than £20 why mess about with it?

 

[tamz]

There is no need to mess about with anything. It needs a washer, fixed it 5 minutes, minimum charge to the customer.