Constant hot water

[doorstop12]

Hi guys

An engineer came to service the boiler last week. It passed and my central heating is working nicely. However, I seem to now have constant hot water... and it's much hotter than usual...

I have an old (non combi) Myson Apollo Fanfare boiler so I use the timer settings on the control panel in the airing cupboard to select when to fire up the heating, and the hot water (separately).

To try to diagnose the problem, I've set the hot water setting to "off", but still the water gets hot...

I've ensured that the immersion heater is off, but still the water gets hot...(the only time the water usually gets this hot is on the rare occasion that I use the immersion).

I've checked that the mid position 3 way valve is on "auto".

The thermostat on the boiler was on "high" (the engineer did this) so I've moved it to "low" as it had always been before.

Any ideas what could be wrong? The boiler is only firing up line with the control panel settings, not of its own accord.

Many thanks

 

[CBW]

Sounds like a 3 port valve fault, stuck in mid position

 

[doorstop12]

Thanks. Is there a fix or is it just a matter of replacing it?

 

[Madrab]

If you follow the 2 pipes out of each side of the 3 port valve, usually the right one will go to the hot water cylinder (B) the left one will head off to the central heating (A).
When only the central heating is on (with hot water off) does pipe B still get hot all the way to the cylinder?

Looking at your hot water cylinder thermostat too, it seems awful low, it should be set at 60Deg.

 

[doorstop12]

If you follow the 2 pipes out of each side of the 3 port valve, usually the right one will go to the hot water cylinder (B) the left one will head off to the central heating (A).
When only the central heating is on (with hot water off) does pipe B still get hot all the way to the cylinder?

Looking at your hot water cylinder thermostat too, it seems awful low, it should be set at 60Deg.

Yes it does. And thanks- stat now up to 60.

 

[CBW]

Thanks. Is there a fix or is it just a matter of replacing it?

That can depend on which part has failed, probably quicker to replace the head.

 

[doorstop12]

That can depend on which part has failed, probably quicker to replace the head.

Thank you. Based on the info above, is it guaranteed to fix the problem or is there anything I can check to see whether it's likely to?

 

[Harry Bloomfield]

Thank you. Based on the info above, is it guaranteed to fix the problem or is there anything I can check to see whether it's likely to?

To test it, enable both HW and CH at the clock/timer, turn HW and CH stats down to minimum and ensure your boiler is not firing.

Now turn the HW stat up to full, boiler should fire, pump and the 3-port should turn/rotate adjust itself to allow heated water to cylinder. Turn the HW stat to minimum.

Turn the CH stat to maximum, boiler should fire, pump and 3-port should turn to allow heated water to your heating system.

Middle pipe if the 3-port is the one from the boiler.

It might be worth removing the actuator/ head of the 3-port and seeing if the D shaped valve spindle itself can be turned. You should be almost able to turn it with your bare fingers - be aware that some valves are only designed to rotate in one direction, do not try to force it the wrong way, rotate that in full circles.

 

[doorstop12]

Many thanks for taking the time to write that.

I've checked that the boiler fires / doesn't fire depending on the stats - both seem to be working fine.

Forgive my ignorance but when you say "pump and the 3-port should turn/rotate" what am I actually looking / listening for?

 

[doorstop12]

 

[Harry Bloomfield]

Many thanks for taking the time to write that.

I've checked that the boiler fires / doesn't fire depending on the stats - both seem to be working fine.

Forgive my ignorance but when you say "pump and the 3-port should turn/rotate" what am I actually looking / listening for?

The pump running should be fairly obvious from the noise and the noise of flowing water in the pipes. The 3-port will sound fairly quiet, it uses a small motor similar to that used in an electric clock, but you should hear the clicking of the micro-switches as it moves. It only takes a minute or so to move to a new position. Depending on the type of 3-port, you might hear a fast and brief whirl, if it's a spring return type of actuator.

If it's not clear, the actuator is the upper part in those two photo you posted above. The valve is the water part below with 3 pipes, hence calling it a 3-port.

 

[doorstop12]

Thanks again.

I've used the timer to request heating and hot water separately.

Pump seems to be fine for both.

For hot water, the 3-port makes a rapid whirling sound for a second before a single click.

For heating, it seems to just click straightaway...

I set the timer to request hot water only and it works fine. However, I was expecting the radiators to get hot as well, but they didn't. Yet when I request heating only, the water continues to get hot...