Camray II - possible thermostat or CH pump prob?

[Ookysoft]

The boiler went cold although powered & the CH pump was running, front panel stat set to 90 degrees.

I determined that the front panel thermostat was not working [ power into but not out of ] and assumed that is the problem.

As it was cold and lodgers begging for hot water, I bypassed the front thermostat and the burner ran. All seemed ok but I wasn't just going to leave it, a 10 minute burst to warm it up then maybe 5 minute bursts every 10 mins or so until the HW cylinder was hot.

However, I heard air rushing through pipes to the header in the loft [ an interesting noise ] so assumed the water in the boiler was super-heating to steam.

I then discover that though the CH pump is scorching hot and humming as though it is running, it's not pumping though.

I Bled the pump [ no air - just a few drips of black water ], bashed it a bit & it seems to run ok now.

The Thermostat seemed to start behaving [ set it to 85 ] by switching on and then off, but stayed off - after some fiddling up and down the temperature scale & switching on and off at the mains [ no real reasoning here ] it switched on and had behaved since.

Opinion please....

Is my initial diagnosis that the thermostat is broken probably true? & I should now replace it as a preventative measure?

Did I let it overheat the boiler water letting it run without thermostat and that overheated water siezed the pump? So the pump is probably ok - or should I be prepared to swap that out too?

Is black water from bleeding the pump [ only got a little water, is it supposed to 'flow' when bleeding? ] a sign it's gunged up?

Or any other thoughts?

What's a good temperature to set this thing anyway? 85?

 

[oilman]

The boiler went cold although powered & the CH pump was running, front panel stat set to 90 degrees.

Too hot. set it to between 70 and 80.

I determined that the front panel thermostat was not working [ power into but not out of ] and assumed that is the problem.

Later you say pump is siezed, so stat may be ok.

As it was cold and lodgers begging for hot water, I bypassed the front thermostat and the burner ran. All seemed ok but I wasn't just going to leave it, a 10 minute burst to warm it up then maybe 5 minute bursts every 10 mins or so until the HW cylinder was hot.

You should have an immersion heater for backup. You will have a hard time explaining why you bypassed a thermostat.

However, I heard air rushing through pipes to the header in the loft [ an interesting noise ] so assumed the water in the boiler was super-heating to steam.

I then discover that though the CH pump is scorching hot and humming as though it is running, it's not pumping though.

I Bled the pump [ no air - just a few drips of black water ], bashed it a bit & it seems to run ok now.

You have paying guests. Stop being a tight wad, and run your establishment professionally. Replace the pump. You should also clean and flush the system and fit a magnetic filter on the boiler return.

The Thermostat seemed to start behaving [ set it to 85 ] by switching on and then off, but stayed off - after some fiddling up and down the temperature scale & switching on and off at the mains [ no real reasoning here ] it switched on and had behaved since.

Opinion please....

Is my initial diagnosis that the thermostat is broken probably true? & I should now replace it as a preventative measure?

If in doubt, replace the stat. It is a safety device.

Did I let it overheat the boiler water letting it run without thermostat and that overheated water siezed the pump? So the pump is probably ok - or should I be prepared to swap that out too?

See above.

Is black water from bleeding the pump [ only got a little water, is it supposed to 'flow' when bleeding? ] a sign it's gunged up?

Or any other thoughts?

What's a good temperature to set this thing anyway? 85?

Black water is excessive magnetite. If the water is not clear, the contamination is excessive. Temperature should be as low as will provide hot water at the right temperature. Supposed to be 60 deg, but IMO that's a bit high.

 

[Ookysoft]

I appreciate the temp was set too high - surprised me, guessing 1 of the lodgers has been fiddling. I normally have it at 80 but will drop it a tad.

I determined the stat wasn't working as there was no 'click' as it turned through the range and a meter across the live into the stat and a neutral showed a voltage but the 'out' of the stat showed no voltage anywhere across the range with a cool boiler.

I do have an emersion but it's not as effective regenerating the cylinder.

Hmmmm! Never been called a tightwad before - if I can't fix it, I do replace it!

I think, so far and for my own comfort, I'll get the spares at least ready to replace.

Yeah, I run the hot water HOT - though scalding, when 3 hit the shower in 30 minutes & tend to wallow, much lower temperature = cold showers! Which might not be such a bad thing actually.............

Thank you very much for your reply!