Blockage solutions

Hello

My boiler switches on for a while and then switches off. There is a device that looks like a pump which seems to have the job of splitting the output of the boiler between hot water and central heating. This device is vibrating and seems to be working but its inlet pipe is hot but both outlet pipes are cold. I suspect that it is jammed. Will bleeding the radiators help? If I add chemicals to the system to dissolve any gunk will I be able to flush the system by myself or is it a job best left to professionals? Many thanks.

Further to my previous post: The plot thickens.

We recently had work done in the bathroom where a radiator was replaced. I think that the plumbers probably drained the system of water. I opened a valve at the bottom of the pipes under the boiler near the floor and about a cup of water came out and no more. If the entire system had water then I'd expect that it would gush with water. I tried to bleed the radiators and got nothing: no air, no water, no nothing. When I switched the system on (bad idea?) It started OK but after a while I had boiling water feeding UP into the feeder tank.

So if I'm right and the whole system has been bled dry - how do I fill it with water? Any suggestions appreciated.

How long ago was the system drained and has it been running since - presumably you have had hot water at some point since the bathroom was completed?

Opening the draincock wouldn't necessarily resulted in a flood of water - you would need to open a few air vents to allow the water to get out of the system.

Depending on the type of system you have - if it's open vented then have a look at the header tank and check if it has water in it as a start point.

Check if your pump is running
Check if you can move the three port valve manually using the lever on the side of the motor housing (the thing that you described in your first post as looking like a pump)

can you not calll the people who drained the system they do have a duty of care to leave you in the state they found you??

Hello

The system has only been turned on recently (yesterday). We have a separate little immersion heater for hot water so we keep the gas off during the Summer. The header tank had very little water in it but is full now. As for getting the plumbers back - its a long story. We rent and the landlord has been fighting with the plumbers since they finished the job - this has not been the only problem. Now the landlord is overseas and we are cold...

Anyway, I'm learning about central heating quite quickly. The thing that has a hot pipe attached to it is a sunvic motorised valve (sd1701). It doesn't have a lever on it or anything that looks like a manual override. I can hear the valve closing when the system is switched off. Above this valve is a pump that does seem to work.

Thanks for your comments. Any more would be appreciated.

Me again.

Over the course of a few evenings I seem to be moving some sort of blockage further along the pipes. At first I thought the motorised valve was at fault but I've now removed that and opened the valve by hand. Hot water is flowing through the pipes. Last night the first radiator heated up but further along the pipe it just got cooler and by the time the pipe reached the second radiator it had cooled completely. The HOWTO section says that this is due to the system not being balanced. What does that mean?

Thanks