Faulty heating at christmas

[WHATSAHAMMER4]

Hello, please help.

I'll cut to the chase...

My boiler keeps cutting out too early, it lights for around 20 seconds then drops out. My upstairs rads are hot but my downstairs aren't.
My hot water is piping hot though.

Boiler: Ideal Classic FF250
Age 4 years
Things I have tried...
Header tank is full and ball valve operational
Checked pump is working ok even tried slowing it down to give the boiler more time to heat the water. Pump is working perfectly
Set motorized valve to manual. There was no resistance when I moved the arm and it made no difference to the rad temps. Turned up the water stat and heard the motor move.
The stat on the boiler is set to highest, room stat has "narrow click". It's set to 20degrees and the room is around 10
The outlet pipe from the boiler is very hot but the inlet is luke warm
I have turned off all of the rads and turned the furthest one on to see if air comes through but that didn't happen.
My downstars rads are all hot at the top and cool at the bottom

Now I'm out of ideas, could the boiler itself be overheating? I haven't a clue about heating. please help I have a house full on Christmas day

Thank You

 

[JohnD]

Sounds like poor circulation to my amateur ear. Rads hot at top, cold at bottom. Boiler cutting out, could be when it hits temperature quickly.

Something wrong with the pump? Is the pump very hot?

Or the motorised valve (hot water very hot could mean too much water is circulating round the cylinder instead of going to the rads)? Is the pipe from the valve, that goes to the cylinder, hotter than the one that goes to the rads?

Or sludge blockage. What colour is the water when you bleed rads; and, do they get much gas in them? What do you know about the cleanliness of the system, and what corrosion inhibitor does it contain?

 

[WHATSAHAMMER4]

Thanks for your reply,

The pump is very hot, too hot to hold your hand on.

The pipe to the cylinder is very slightly hotter but really not a lot

When I bled the rads in the summer the water was clear.

Sentinel x100 inhibitor is in it

Up intill about a month ago they were all red hot top to bottom.

 

[Agile]

"""Checked pump is working ok even tried slowing it down to give the boiler more time to heat the water. Pump is working perfectly"""

I am always suspicious when I read that kind of thing when the fault points to a non functioning pump!

Can you explain EXACTLY how you can be so sure its "working ok".

Tony

 

[WHATSAHAMMER4]

If I put my hand on the pump it vibrates like something inside it is off centre, when I slow it, it vibrates more slowley.

Sorry, I've just realised how stupid that sounds out loud.

Is it likely to be the pump then?

 

[Agile]

I suppose it does not matter if you dont know how to check it properly.

Professionally, I have to do it properly every time!

Turning?

Torque?

Impeller clear?

Tony

 

[WHATSAHAMMER4]

I did read somwhere that I could try to turn it with a flathead screwdriver but I only have a bolt shaped blanking plate in the centre.

What would you recommend I do to test it?

 

[Agile]

See the FAQ on this site.

Even if its turning then you still have to remove the pump head to see if the impeller is present and clear!

Tony

 

[WHATSAHAMMER4]

Thanks a lot for your help mate

 

[ChrisR]

If you buy a pump made by "Circulating Pumps" you'll be able to just change the head.
To give you best chance of warm rads downstairs, turn HW off and close upstairs rads, with boiler temp on max.

 

[WHATSAHAMMER4]

Cheers Mate,

I have turned off the HW and all but one rad. I was told that if there was any air in the system then this would flush it out. It was the furthest one that I left on then worked backwards. When downstairs were all on they were piping hot but when I turned the upstairs back on the downstairs cooled to warm and there was no air. I even opened the vent pipes in the airing cupboard but they just expelled water.

I have removed the centre nut on the pump and pushed a small screwdriver in and it span round. I was told that this would prove that the pump was working, I'm not sure about the advice I'm getting though.

Would the next step be to get new pump?

Just checked out Circulating Pumps, looks dead easy to change the head. Suites me fine

 

[Agile]

It probably just needs balancing!

Close all the upstairs rads and then open them just a half turn !

Tony

 

[breezer]

i have no idea if it is the pump, but you can get one today from b & q (assuming they havent sold out)

 

[ChrisR]

Un-balancedness wouldn't make the boiler stop after 20 seconds.

You could remove the head from the pump and see if it's clogged between the 2 plates. Then power it up and see if it's easy to stop with one fnger - it shouldn't be.
While it's off see how hard it is to undo the big pump nuts.

If you get a B&Q Wilo or Grundfos pump you'll have to change the whole thing which can be harder - depends on your luck, but they will fit between the pump valves, same distance.
Not sure which models the other sheds sell.