Boiler/Pump Problem - Ideal Classic

[whookam]

I have bought a flat with what looks like a very old Ideal Classic LXFF Boiler and a Grundfos UPS 15-50 pump. I recently drained the system to replace some leaking pipework but I'm now having problems getting the system to fire up again. I thought I would go through what is happening in case one of you kind people can help me. (bearing in mind that I no little-to-nothing about CH or the correct terms!)

I have refilled the system and have checked all the radiators. They all seem to be free of air. If I try to fire up the boiler it will run for a few seconds before switching off. The casing of the boiler is warm. The boiler is set to 6 and the overheat switch is normal.

I can not hear anything particular coming from the pump but can honestly not remember how much noise the pump has ever made. It seems to be pretty silent and I can sense no vibration to indicate it is doing anything. I have tried bleeding the pump and get a contstant but slight trickle. I have turned the pump using a screwdriver and it seems to be free. The pump is warm/hot to the touch.

I have hot water tank that appears to be empty and is cold to the touch. None of the radiators are warm and I have no hot water form the taps.

Any suggestions on what could be wrong. My thought are that pump is dead but it seems starnge that this would go when I'm just replacing existing pipework. Any suggestions would be very helpful.

I am due to be replacing the boiler in the next few months but I don't think I can stand the cold showers much longer.

Cheers,
Steve

 

[ChrisR]

Pump has to be suspect - see if it has mains on it, and you can tell if it's turning by poking your screwdriver up it.
Or just lots of air on the boiler - can be hard to get out. Look for air bleed points above the boiler - eg by the HW cylinder heating pipes from the boiler.

 

[Agile]

Do you have an electric immersion heater fitted in the hot water cylinder which you can switch on?

Tony

 

[whookam]

Thanks for the replies.

I do have an immersion heater in the hot tank but I'm not sure that there is any water in the tank (sounds empty when tapped) and also wouldn't my pump need to be working to get the water around the system?

I tried a couple of things last night. I switched the pump on by itself which was not easy as whoever had installed it had wired the pump and boiler to the same junction box. Anyway, when the pump is turned on by itself I can hear absolutley nothing. Are there any reasons why a pump may not work apart from malfunction? Ie. Air in the system? I would have thought that even with air in the system the pump would make some kind of noise if not more than usual.

I am considering ordering a new replacment pump. Do you feel that a straight swap for a new pump is something that a non-expert can do? I seem to have a valve either side of the pump which I assume will shut off the flow and allow me to take off the old pump and put in the new one?

Considering that I am changing this whole system in a few months, I don't want to spend a fortune but the pump on its own is around £50.

Cheers.

 

[ChrisR]

If you have hot water coming out of your tap then you have water in the tank.

Why don't you simply test the pump the way I told you instead of trying to guess what it might sound like? You've already had a screwdriver in there, just measure volts. Maybe it isn't connected

Changing a pump can be a 5 minute or 5 hour job, depending on all sorts. If the pump valves are quarter turn variety, expect them to leak.

 

[ollski]

Did you bleed the pipework in the loft or airing cupboard or whatever?. if not you may well have burnt the pump out. The pump and boiler should be wired together by the way.

 

[whookam]

As far as I can tell the pump has water in it as I get a trickle when I undo the screw on the front and also it is very hot to the touch as if it was full of the hot water from the boiler. I didn't run the pump or boiler until I had bled the system as much as I could.

Chris, I'll double-check to see that the pump is recieving mains power tonight when I get home. Wierdly enough we did have an electrician in the day it packed up to put in a new consumer circuit but I can't see what he could have done to effect this as the boiler is recieving power and as mentioned the pump and boiler are wired together (thanks for confiming this is normal ollski).

Also, just to confirm this, I have no hot water from taps or in the radiators.

One more thing. Does the boiler actually have any control over the pump? In other words if the boiler and pump are switched on does the pump just keep going regardless of what the boiler is doing? It's just that I read about boilers being able to switch off pumps to stop them overheating but I don't have any electrical connection between boiler and pump. I guess I just have a different type of system.

Cheers.

 

[ollski]

you need to fire it up so that the boiler is calling then take the screw out of the front of the pump and just put a screwdriver in gently to confirm it is turning....try this first. Bleeding the rads does nothing to clear an air lock in the pipes, have you found and bled the bleed points on the highest sections of the pipework?.

 

[Agile]

If the pump is hot and the pipes are not then the pump is getting heated by its electrical supply.

If you listen with a screwdriver to the ear you should hear a 100 Hz hum from the pump.

The capacitor in the pump has probably failed and is not starting the motor.

You should stop talking about it and get testing it as advised. When powered it might start turning if you give it a twist on the shaft. It may just be the capacitor wire is making a bad contact.

Tony

 

[whookam]

You should stop talking about it and get testing it as advised.

Will do. As soon as I get home from work... promise.

 

[whookam]

Well, I got home from work and set about to check everything you guys suggested.

The boiler and pump had been off all day so the first thing I did was to check that everything was cold to the touch which it was (of course).

I thought now that if I turned on the pump only and it got warm I could clarify that it was being heated by the electric supply as mentioned and not by the water from the boiler.

I turned on the pump (screwdriver by ear ) and got a bit of a surprise. The pump imediatley sprung into life and I could hear the water flowing through the system. I let the pump run for about 10 minutes as I could hear what sounded like air in the system. I checked all the radiators and found that one radiator (the one nearest the boiler) had quite a lot of air in it. I drained this radiator before turning on the boiler.

The boiler now seems to be heating everything nicely. Radiators got warm first and then slowly the hot water tank has begun to be filled with hot water. It is still a little noisy so I think there may still be some air in the system. I would like to find this a drain valve higher in the system but can't find anything within my flat. The pipes run through the flat upstairs and into the loft, could there be a valve this high?

Anyway, all seems to be working ok now and I guess it was an air block that seemed to 'work its way out'. Cheers to all.

Steve