Occassional Lockout since replacing simple dial room stat?

glowboy77 · 2 Feb 2011

Howdy,

I have never had any problems with the old dial type stat but have changed it this winter for a wired programmable type.

Since then, on occassion the boiler has gone to lockout and i have had to reset. Anyway, i watched it the other day and the following seems to be happening which is causing the lockout;-

-not when boiler is firing but just as boiler is about to fire ie proving ignition, checking for flow etc etc if at this time the room stat temp is reached and therefore clicks off, i hear the motorised valves closing,
- then going to check boiler i find it is flashing red as for lockout, its as if it is sensing this closing of valves ie no flow, as a problem, a quick press of reset and it stays orange ie temp satisfied.

If the room stat clicks off when boiler is firing, the boiler simply stops, valves close and boiler flashes orange ie temp satisfied straight away, and left in standby mode ready to go again.

Anyone any ideas, is my room stat useless (sunvic)??

Should the room stat know what boiler is doing, therefore let it finish it's cycle or run on for a bit??

Help please.

D_Hailsham · 3 Feb 2011

Sunvic is not everybody's favourite manufacturer.

Which Sunvic do you have

Which motorized valves do you have?

Agile · 3 Feb 2011

You dont say which boiler! Suprima?

It sounds as if you may not have a bypass to enable flow to continue when the valves close.

It also needs checking that the pump is connected to the boiler to enable it to over run.

Tony

glowboy77 · 3 Feb 2011

D Hailsham,

Its a sunvic tlx 6501, valves also sunvic (2x 2 port valves).

Agile,

there is a bypass valve fitted, how do i check if pump connected to boiler? its a suprima 50L.

picasso · 3 Feb 2011

glowboy77 said:
-not when boiler is firing but just as boiler is about to fire ie proving ignition, checking for flow etc etc if at this time the room stat temp is reached and therefore clicks off, i hear the motorised valves closing,
- then going to check boiler i find it is flashing red as for lockout, its as if it is sensing this closing of valves ie no flow, as a problem, a quick press of reset and it stays orange ie temp satisfied.

not much help for your problem but why turn down the room stat just as the boiler is about to fire, the room is hardly likely to reach the set temperature if the boiler hasnt fired.

Agile · 3 Feb 2011

How is the bypass set?

You will have to follow pump wiring and see if it goes back to the left terminals on the boiler choc block.

Does the boiler have the new design PCB or the old original type?

Tony

glowboy77 · 3 Feb 2011

not much help for your problem but why turn down the room stat just as the boiler is about to fire, the room is hardly likely to reach the set temperature if the boiler hasnt fired.

I do not turn down stat, i mean when the desired stat temp is reached. It is not me turning the thing down, it is when the stat temp is reached as the boiler is about to fire. When boiler temp satisfied, no problem, when boiler running no problem, when boiler about to run and stat clicks off, LOCKOUT!!??

Valves are RANGE upon closer inspection.

Cheers,

glowboy77 · 3 Feb 2011

New style PCB and yes it has already been replaced!!

What do you mean how is bypass set?? Shall i post pics after??

picasso · 3 Feb 2011

sorry mate you have totally lost me

how can the stat reach temp if the boiler is trying to ignite ? I am sure you know what you mean, meanwhile check that you dont have the "call" and " satisfied" in the wrong terminal in the stat.

Agile · 3 Feb 2011

I doubt a photo will help but it might.

I am interested to know what type it is and what setting its on.

Tony

glowboy77 · 3 Feb 2011

I.ll check bypass details after as in work.

Say stat temp I want is 20°c, and Its at 19.5, if it goes over to 20 as boiler is about to fire (but not firing) the stat clicks off, valves close and boiler goes to lockout?
It seems to happen quite often where stat can go up half a degree while boiler waiting to kick in again, hence my query about whether stat is useless? Think wiring ok as when demanded at stat, valves open and boiler fires. When satisfied they shut.

glowboy77 · 3 Feb 2011

Bypass is SBV 33, and white thread indicator is at the 0.1 bar mark on the red sleeve.

That ok?

Agile · 3 Feb 2011

Thats all fine and the setting could probably be a little higher. But we can discount that as part of the problem if its connected correctly.

Now there is the pump connection for the over run to be checked!

Tony

glowboy77 · 3 Feb 2011

Ok, thats good.

Boiler in utility downstairs, pump in airing cupboard with a wiring centre for it and valves etc.

What am i looking for??

DP · 3 Feb 2011

Sunvic is not everybody's favourite manufacturer.

DH, why do you say that? Actuator is no different from many others, body is standard that several manufacturers use. MOMO is a far superior valve in that motor only runs to position the valve. I have rarely had to replace MOMO head but replaced plenty syncron motors and actuators.

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Occassional Lockout since replacing simple dial room stat?

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