I've just bled my radiators, now they don't work at all...

We have an old gas boiler downstairs, a copper hot water tank upstairs and the central heating pump and manifolds are under the floor of the landing. There's a header tank in the loft. I know almost nothing about plumbing!

We last used the radiators a week ago. The hot water is used daily. My wife was complaining about it making a noise in the morning, so I thought to try bleeding the radiators. They do fill up with air quite often.

When I bled the upstairs radiators, a little air came out, then stopped. No water. I suspected the header tank and found it empty, with the ball valve stuck shut. A few prods got it working again and the system filled with water; I bled all the radiators again and water flowed out of all of them as expected.

Now - they don't get hot. At all. Stone cold. The hot water still seems to work.

I've got to the manifolds, and the radiators' source manifold is hot, but not as untouchably hot as the pipe to the water tank. Some of the pipes coming out of the source manifold are just warm, others cool. The return pipes are cold.

I can hear the hot water/radiator selector valve moving when I click the switch over, but I've no idea if it's actually working. It's a Danfoss HSA3 if that means anything to anyone.

Everything was working before I bled the radiators and found out about the empty header tank.

What should I do next to figure out what's wrong? (other than 'call a plumber' - I can't afford to!)

Thanks,
Rick.

See FAQs 9,14 and 21 here
//www.diynot.com/forums/viewtopic.php?t=175736

Check if any water in header tank. If there is, then probably a blocked feed.

Thanks folks.

Yes, there's water in the header tank (now that I've freed the ball valve)

The pump seems to be working - I've bled it, the hot water tank is getting hot and I can hear the difference in water flow into its heat exchanger coil if I change the pump's speed.

Still hardly anything to the radiators though. I have managed to get one just vaguely warm by turning off all the others, but only just. It's as if there's barely a trickle of warm water getting to them.

Am I right in thinking that if I move the lever on the Danfoss valve to Manual, that it opens the flow to the central heating? I tried that and it made no difference.

I've tried to locate a drain on the ground floor in case I need to drain the system, but there doesn't appear to be one. Not on any of the radiators or exposed pipes, anyway. The only one I can find is on the back of the boiler, but that's not the lowest point. The system is old and obviously "cowboy'ed", like everything else in this place.

It occurred to me after letting the tank refill the system, that muck might have got in from the tank being refilled. Like if you let the fuel tank on a car get too low and it sucks the muck off the bottom into the lines. I really hope not... but it's looking like it might be that to me at the moment.

I need to put the floor boards back now; my wife's home. I'm left toying with ideas of connecting a hose pipe to the system somehow, and blasting the rubbish out!

Can you check the pump operation as per FAQ 20 in the above link

I'll try tomorrow. It's really difficult to get to because of where it's fitted right next to a beam under the floor.

Do I undo the bolts that fix the round part to the square part, and remove the round part to test?

I take it I have to isolate the water either side of the pump first...

Follow the outlet from the header tank to where it joins the main heating pipework and hit it hard with the stave of a hammer, or similar. If you're lucky, it will dislodge the blockage that is stopping the header feeding the system.
As an old plumber once said to me; for hitting with hammer, £5
For knowing WHERE to hit with hammer, £50

Sorry for the delay updating - had other problems come up

I tried hammering the pipe at the joint; no effect. Thanks though.

I've had the pump head off and cleaned the rotor. It was a little scratchy at first but rotates freely now. It definitely works. I couldn't get the union nuts off; the pump turned instead of the nuts unscrewing. That allowed me to get to the hex-head bolts though so I just removed the motor housing.

The water that came out was muddy and left a rusty-looking sediment in the tub. I also cleaned out the remains in the header tank - thick, rusty-brown sludge.

My next step (I think) is to put it all back together, put some cleaner in (got Fernox F3) and see if it will circulate enough to clean out the system.

My problem now is that there is no drain on bottom of the system. The only drain on the whole thing is the one on the back of the boiler; on the wall above the ground floor radiators. Typical.

I managed to drain the system enough to remove the pump (didn't trust the isolating valves to be effective) through the radiator bleed. I doubt that's good enough to drain the system after I've had the cleaner in though.

So I need to fit a drain point somewhere. I'm thinking of cracking the nut on one end of a radiator and letting the system (very) slowly drain off there, then fitting a different end with a drain point. Unless there is a drain thing that can be fitted into the middle of microbore pipe.

I would certainly appreciate any further advice. I'm still wondering if I need to have it power flushed, although I would prefer to avoid the expense if at all possible. I'm also concerned that it might not solve the problem anyway; I don't know how effective it is.

Cheers,
Rick.

I have a radiator valve connected to a length of hose. Close off both valves on the lowest radiator, and with a cloth/tray under the joint, disconnect one of the valves from the rad and replace with your valve+hose. You won't lose much water in the time it takes to undo one valve and replace with the other.

Then run the hose somewhere suitable, and open both valves on the rad - job done and you can then fit a new vlave with integral drain off if you wish.

That sounds a good idea - off to B+Q it is then.

Thanks!

As you said, this could go on one of the downstairs rad, nearest the outside. www.wickes.co.uk/invt/160089

Perhaps crud from the tank has got lodged at the manifold. Perhaps cutting into the larger pipe just before the manifold is easier than cutting into microbore. (Leave enough length of pipe at manifold end so you can join it again!) If enough movement in pipework you may be able to dislodge!

Again, perhaps a backwards/reverse flow from rad to manifold with hose pressure when cut open would flush it out. Although that could get very messy