Discussion
A friend has recently bought a flat.
It has a Tribune HE hot water tank with what look like two immersion heaters, one linked to a socket which says "off peak w/htr" and one linked to a scoket which says "on peak w/htr".
If neither of these switches is on, she doesn't have hot water. IF either of them is on though, she gets hot water which then comes straight out of the water tank and pours down an overflow and across the car park.... This happens about 40mins to an hour after switching on one of the wall sockets.
WTF?!?!?!?
(the expansion vessel is a Zilmet Spa 110-Ultra Pro if that helps!)
It has a Tribune HE hot water tank with what look like two immersion heaters, one linked to a socket which says "off peak w/htr" and one linked to a scoket which says "on peak w/htr".
If neither of these switches is on, she doesn't have hot water. IF either of them is on though, she gets hot water which then comes straight out of the water tank and pours down an overflow and across the car park.... This happens about 40mins to an hour after switching on one of the wall sockets.
WTF?!?!?!?
(the expansion vessel is a Zilmet Spa 110-Ultra Pro if that helps!)
Well spotted on mentioning the pressure vessel!
If it's failed internally, it could cause this. The vessel takes the expansion when the water heats, hence it opens the safety valve if it's not operating correctly.
HOWEVER.
There are some other possibilities.
The PRV should be reducing pressure to the value marked on it - if it isn't this will happen.
The Temperature Relief valve will open if the water temperature exceeds 90.
Turn the inlet valve closed. Run the hot 'til it stops. See if there is pressure at the schrader (sp?) valve on the vessel. It should be set half a bar under incoming.
PS The cheap rate switch heats the cylinder at night, the other one is just for boosting in the daytime and only heats the top (stratification allowing...)
If it's failed internally, it could cause this. The vessel takes the expansion when the water heats, hence it opens the safety valve if it's not operating correctly.
HOWEVER.
There are some other possibilities.
The PRV should be reducing pressure to the value marked on it - if it isn't this will happen.
The Temperature Relief valve will open if the water temperature exceeds 90.
Turn the inlet valve closed. Run the hot 'til it stops. See if there is pressure at the schrader (sp?) valve on the vessel. It should be set half a bar under incoming.
PS The cheap rate switch heats the cylinder at night, the other one is just for boosting in the daytime and only heats the top (stratification allowing...)
A quick method of checking if the vessel is gone, depending on how it is fixed.
Try lifting it out of its bracket, if it is extremely heavy, chances are the diaphragm has ruptured. You should be able to lift it with one hand in its correct state.
When you press in the schrader valve, if water comes out. It is buggered!
Try lifting it out of its bracket, if it is extremely heavy, chances are the diaphragm has ruptured. You should be able to lift it with one hand in its correct state.
When you press in the schrader valve, if water comes out. It is buggered!
Jasandjules said:
Ok, there is a red valve with 90degree and 7 Bar on it which comes from the pressure unit, and water immediately gushed out. It also felt quite heavy but it is bolted in place.
So all in all it does seem like the diaphragm has gone. Thanks chaps !
Sounds like the Temperature/Pressure relief valve. That is normal. So all in all it does seem like the diaphragm has gone. Thanks chaps !
There should be a tyre valve on top of the expansion vessel. There may be an odd looking cap covering it. Push the valve in, as if you were deflating a tyre, if water comes out, its broken!
If no water escapes, there may be no pressure on the air side of the vessel. As Ferg said. Turn off the water and open a hot tap to de-pressurise the hot water. Connect a pump with a pressure gauge to the schrader valve and pump it to what ever it says on the vessel. Usually between 0.5 and 1 Bar.
Ricky_M said:
There should be a tyre valve on top of the expansion vessel. There may be an odd looking cap covering it. Push the valve in, as if you were deflating a tyre, if water comes out, its broken!
Ok, I've found that, it was hidden under a cap indeed, which unscrewed! Poked it with some scissors, and no water came out... So that's a start. I am thinking I will need to get a bicycle pump to pump it up then?
Jasandjules said:
Ferg said:
That'll be fine. 
Thank you! Just need to find something to fit over the valve now to pump it up - looks the same size as a car valve so I am hoping a bike pump will do it and I'll use my tyre checker to pump it to 2.5 Bar (thing on it says 3 Bar I think).I pump them with a bike pump, it's a normal schrader valve.
Right, bike pump bought, valve pumped. Also bought a car tyre pressure guage to check it BUT when the tyre pressure guage goes on it doesn't do anything (I suppose I was a bit optimisitic to think that it would all work smoothly for me).. Soooo, what do I need to use to check the pressure?
Jasandjules said:
Right, bike pump bought, valve pumped. Also bought a car tyre pressure guage to check it BUT when the tyre pressure guage goes on it doesn't do anything (I suppose I was a bit optimisitic to think that it would all work smoothly for me).. Soooo, what do I need to use to check the pressure?
That should do it.Silent1 said:
Jasandjules said:
Right, bike pump bought, valve pumped. Also bought a car tyre pressure guage to check it BUT when the tyre pressure guage goes on it doesn't do anything (I suppose I was a bit optimisitic to think that it would all work smoothly for me).. Soooo, what do I need to use to check the pressure?
That should do it.I must say, the water is on by all accounts and so far so good, it's not just pouring it out the overflow, but she said it did this before for a while...
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