Is this right?

[nstreet]

We have an ideal mexico boiler for our HW and CH, it is controlled by a switchmaster sm400 timeclock, one of the old mechanical ones. The odd thing is that when the timeclock is not programmed to provide heat or hw the boiler will turn on if we use hot water. We have also noticed that in the evenings when the room stat controls the temperature, after the initial couple of hours, we can put the stat up a degree and and nothing happens for a while, not even the circulating pump, but then at 20:50 the system will fire up without fail. Any one have any ideas please?

 

[breezer]

i am not a plumber or heating engineer, but to me it sounds though everything is working fine.

I am going to presume your boiler is a combi, when you turn on a hot tap, irsective of what your timer says, the boiler will come on to heat the hot water, if it didn't you would have no hot water.

as for 20:50 you say it always does it at this time, that would indicate the timer is set to do something at 20:50 as the boiler has no idea and does not care what the time really is, it must be something the timer is telling it to do at 20:50

 

[nstreet]

Thanks for the reply breezer,

As far as I am aware the boiler isn't a combi as we have a hot water cylinder

The time switch is set to come on at 16:00 and go off at 21:00.As its a mechanical one there are no other settings. Its just really odd that it fires up at 20:50 every night without fail.

Even though I can hear the room stat 'click on' with the increase in temperature the bolier and/or pumps may not do anything for a long while(upto 30 minutes), perhaps the timer or room stat or both are knackered?

 

[breezer]

ok then it was just a thought. but here is anoter one, as its a mechanical timerit may not be acurate, and although set for 20:50 it may be "slow" also i am wondering the it may be (only maybe) that the off and on buttons have been moved so that it comes on at 21:00

years ago when i was young i moved the "little buttons" and thats what our heating did

 

[masona]

I had a similar problem, mine just clip off the bracket and I blew the dusts out,spray it with Switch (can't remember if that's the right name for cleaning terminal contacts).

 

[nstreet]

Here's the really strange bit just happened a few hours ago.

The demand for heat and hw is off at the timeswitch. Its not enabled until 16:00

Whilst cooking lunch the boiler fired up, but is not producing heat as the radiators aren't getting warm so i assume its heating the water in the cylinder as the cylinder stat must have sent the demand.

The room stat was set at 15 degrees, turned it to 25 and the boiler stops. odd? Changed it back to 15 and the boiler fires up again, but the motorised valve is opened so no heat.

The stat is now at 15, the time clock has switched on, as i changed the startup to 15:00 instead of 16:00, the boiler has fired up and the radiators are getting warm.

Would you assume that the control has'nt been wired correctly?

 

[AnonymousImport]

Have you just moved into the house or is this a recent problem?

Sounds to me like it has been wired completly wrong!

Bit more info and I may be able to help.

Gasman

 

[nstreet]

Hi Gasman,

we only moved in 3 weeks ago. I suspected something wasn't quite right from day one. Anything you need to know just ask. Many thanks