Bubbling water

[andypotter]

Please help, my hot water doesn't cut out properly. When switched on and the temp on the thermostat is set at 55c it doesn't switch off, it keeps going till a loud bubbling/banging noise comes from the coldwater tank above, and then it switches off. I've tried changing the thermostat for a new one but I still get the same result.

any ideas thanks

 

[JohnD]

give us a few clues

is it an immersion heater in a hot water cylinder?

Is a gas boiler involved?

Is the water supplied from a cold water tank? Where is it?

how hot is the water that comes out through the taps?

how do you know if the wiring the the thermostat has been correctly done?

what shape is the thermostat, and where did you fit it?

 

[bengasman]

Damn, crystal ball never works on fridays.

 

[andypotter]

the water is heated by a coil inside the hot water tank.

the thermostat is a honeywell L641, and is an exact replacement for the one that was already fitted so I connected the wiring exactly the same as the previous ( how do I know that the previous one was wired correctly I hear you ask?? well I've bought my father in laws house and it definately use to work). and located in exactly the same place. Also if i have the water on and turn the temp down to 0c it cuts out.

The hot water is linked to a boiler, not a combie boiler.

the cold water is supplied by a tank directly above it, there is also a tank above that in the loft.

The temp that comes out of the taps is way hotter than my friends

 

[BingoBongo]

is it hotter than 55 degrees

 

[JohnD]

what temperature is the boiler set to?

what sort of boiler is it? how old is the system?

is the primary flow from the boiler to the cylinder pumped or gravity?

how far is the boiler from the cylinder?

are any of the radiators getting hot?

The Honeywell L641 does not have a zero degrees setting.

I asked you where the stat was, and you did not tell me.

If you turn the knob on the cyl thermostat, it should click as it turns on and off. Turn it slowly and listen. Tell us if and when it clicks. When it is pressed firmly against the metal cylinder (with no insulation in the way) about one third up from the bottom, this click should occur when the temp indicator on the knob is about the same reading as the actual temp of the cylinder, though they can get out of adjustment.

post some pics of the pipes, valves and pump around the boiler and cylinder please

//www.diynot.com/forums/viewtopic.php?t=129539

 

[Paul Barker]

Don't pile the coal up the chimney, plays havoc with back boilers.

 

[andypotter]

what temperature is the boiler set to?

what sort of boiler is it? how old is the system?

is the primary flow from the boiler to the cylinder pumped or gravity?

how far is the boiler from the cylinder?

are any of the radiators getting hot?

The Honeywell L641 does not have a zero degrees setting.

I asked you where the stat was, and you did not tell me.

i will post some pictures soon have sent my double bum to get some batts for camera.



If you turn the knob on the cyl thermostat, it should click as it turns on and off. Turn it slowly and listen. Tell us if and when it clicks. When it is pressed firmly against the metal cylinder (with no insulation in the way) about one third up from the bottom, this click should occur when the temp indicator on the knob is about the same reading as the actual temp of the cylinder, though they can get out of adjustment.

post some pics of the pipes, valves and pump around the boiler and cylinder please

//www.diynot.com/forums/viewtopic.php?t=129539[/QUOTE]


it's set 3 and half out of 6, i've tried turning it down, it just takes longer but still bubble

it's a baxi and is no oolder than 5 years, the system itself is was installed 20 years ago.

I don't know about the primary flow, how do i find out?

the boiler itself is suituated almost directly below i'd say no more than 10 feet of piping away.

yes the bathroom radiator becomes a little aired but only when the hot water tank becomes full of red hot water. I had a new 3 way motorised valve installed last year as the heating was coming on when i turned the hot water but that no longer happens, it's a honeywell valve.

the 0c i was refering to is when i've twisted the dial anti clockwise all the way to the of position.

the stat is located a third of the way up from the bottom of the tank

it clicks on and off at approx 10C( as there is no indication below about 40)

 

[JohnD]

adjust it to a low position where it clicks, and see what temp the cylinder reaches. If it's still too hot, turn it down a fraction, if it's too cold, turn it up a fraction.

Regardless of the numbers indicated by the knob, when the stat clicks, it should switch the boiler. If in fact it does that, then the only problem is that the indicator is out of adjustment.

If however it doesn't then you have some different fault and you will have to do some more investigating or get someone in.

If you buy yourself a thermometer and test the actual temperature of the hot tap water, that will be a start.

Also, climb up into the loft and look at the Feed and Expansion tank which will probably be about 18"x12"x12". I suspect you will find that, when the stat operates, it causes the motorised valve to shut, and there is a brief overpumping of water through the vent pipe (the 22mm copper pipe that curves over the top of the F&E), and this probably causes the noise you mention. If however there are bubbles of air or steam coming up the bottom of the tank this is worse. If you can get someone to turn the cyl stat knob while you watch this will be helpful. Also look at the the depth and colour of the water, and see if there is a layer of silty mud at the bottom of the F&E. It may be brown or black. Do not stir it up into the water.

If you post the photos I asked for, that will help us to identify more about your system that you don't know. I would particularly like to see a pic of the cyl stat so I can see how tightly it is fixed to the cylinder.

 

[numpty1]

check the operation of the boiler stat and replace if ness.

 

[andypotter]

I have uploaded photo's on my profile, i've turned the thermostat right down just waiting to c what happens

 

[andypotter]

i,ve turned it right down and it worked, thanks folks