Coal Fired Boiler Turmoil - Help

[Busybloke]

Just moved into an old 50's ex council house in the middle of nowhere and having radiator problems.

Heating comes from a Charnwood wood/coal fueled boiler with a Grundfos 15/50 pump and two Honeywell T70 thermostats on the outbound and return pipes to the boiler.

NB: The hot water for the taps comes from economy 7 which is fine.

The two thermostats are wired into a switch plate along with the pump and timer. Whoever wired it must have liked choc boxes and multi colors as it's like mixed wool in there!

I figured the pump wasn't running and detached it from the spaghetti and put a plug on it and it worked fine and the radiators warmed up throughout the house. Should I assume that the thermostats weren't working (I had the outbound set at 85 and the return at 45) and not sending a signal to switch the pump on?

Any help would be great as it's a bit parky. I could just leave the pump on without a thermostat connection, but I'm unsure if that is a good idea - it seems to make all the radiators warmish - but that's it.

Any thoughts?

 

[Busybloke]

Sorry - I meant to say the problem was that only some of the rads seemed to come on - they were all bled. With me wiring the pump directly, they all now get warmish - just want it working properly with thermostats like a proper house

 

[Terrywookfit]

Are you sure that the S/F boiler does not heat the water?

The stats on the F/R pipes are to control the pump and prevent boiling of the system!!
They should overide the clock to turn the pump on in case of overheating in an off period !!

 

[pure plumbers]

If the system is really that old it sounds like it may need a powerflush, I would recommend this anyway from the sounds of it and them perhaps change the pump.

If you can stop the center impeller on the pump, by taking out the center screw and placing a screwdriver on the nut, then change the pump.

If you are getting some heat through the rads it would indicate that the system needs some work but will function correctly

Pure plumbers

 

[Busybloke]

The boiler definitely heats the water.

Before I disconnected the pump from the thermostat/timer, all that would happen was that the upstairs radiators would become warmish. Now that I've got the pump going directly from the mains (I've put it on setting 1), all the radiators become warmish (which is handy as the only toilet is downstairs, and it's bloomin freezing).

Since I hard wired the pump, I'm deducing that:

The water is getting round ok
The pump side of things works
The rads all work
The boiler works

Is it something to do with the Honeywell thermostats? How could I check? Should I go down to the nearest plumbing center and swap them out? I have a horrible feeling the answer is going to be that I'm missing the obvious.

 

[Terrywookfit]

The most probable reason that some rads work without pump is that they are meant to work that way to dissipate heat !!

Unless you stoke the fire up the rads will not be very warm!!

 

[Busybloke]

Fair point - I've stripped the boiler down and cleaned it out and it burns well and is fueled every day and ash removed every other. I also swept the flu and cleared out the throat plate. I think it burns well and is reguarly riddled and stoked each day.

The only time the radiators came on downstairs (prior to me re-wiring the pump) was one night when I forgot to turn down the air intake down before going to bed, and the misses came down to find the house boiling and the boiler glowing like a nuclear reactor - you live and learn.

All I want to do now is get the system working with the pump reattached to working thermostats.

I think the power flush is also a good idea - can I get something to do that myself or do I need o pay large sums of cash to get someone in (I'm in Hampshire).

 

[Terrywookfit]

The pump should be controlled by the timer!
The stat on the flow should be wired in parallel with the timer contacts and set to 90F so the pump is activated if the temperature reaches this!!
I'm not sure what the stat on the return is supposed to do as I have never encountered one !!