Various central heating problems - CH, pump, rads and pressure

[britishboy7]

Just moved into a 1930's semi and got a few problems with the heating, they are:

1) Potterton Profile 60eL boiler keeps needing to be reset (button under boiler)

2) Only 3 or 4 of the 11 radiators get hot, others stone cold.

3) Water pressure in all taps, hot and cold is very poor apart from kitchen cold tap (mains)

Limited knowledge but I've bled the radiators til water comes out, and the central heating pump is red hot to touch, too hot in fact, as is the pipe going into the top of it. The pipe coming out the bottom though, is cold.

Any advice greatly appreciated

 

[JohnD]

the central heating pump is red hot to touch, too hot in fact, as is the pipe going into the top of it.

Water is not circulating through it. It is being heated by the electrical supply to the motor. Heat is probably rising by convection into the upper pipe.

Disconnect the electricity, remove the central screw from the pump (water will not squirt out, though it may drip), see if you can turn the spindle (it has a screwdriver slot for this purpose). If not, it is jammed, possibly with sediment.

If you can, see if it spins when the power is put back on.

If it does spin but is not pumping, you probably have a blockage, which might be sediment or it might be that a valve, perhaps a pump valve, is closed.

If you suspect a blockage, apply a strong magnet to the copper pipes. The magnet will not be attracted to copper, but it will be attracted through the copper to blockages of black magnetite, which are very common, and result from corrosion of the steel radiators.

The water pressure in the taps is irrelevant, but is probably due to the cold water tank in the loft not being very high above the taps. Have a look in it in case a drowned rat is blocking the outlet.

 

[PullerGas]

No water or limited water in your C/Heating system. Check your F&E tank in the attic or if it's a sealed system, check the pressure gauge.
HTH

 

[britishboy7]

No water or limited water in your C/Heating system. Check your F&E tank in the attic or if it's a sealed system, check the pressure gauge.
HTH

Thanks Puller, the smaller tank in the loft is about half full?

 

[britishboy7]

the central heating pump is red hot to touch, too hot in fact, as is the pipe going into the top of it.

Water is not circulating through it. It is being heated by the electrical supply to the motor. Heat is probably rising by convection into the upper pipe.

Disconnect the electricity, remove the central screw from the pump (water will not squirt out, though it may drip), see if you can turn the spindle (it has a screwdriver slot for this purpose). If not, it is jammed, possibly with sediment.

If you can, see if it spins when the power is put back on.

If it does spin but is not pumping, you probably have a blockage, which might be sediment or it might be that a valve, perhaps a pump valve, is closed.

If you suspect a blockage, apply a strong magnet to the copper pipes. The magnet will not be attracted to copper, but it will be attracted through the copper to blockages of black magnetite, which are very common, and result from corrosion of the steel radiators.

The water pressure in the taps is irrelevant, but is probably due to the cold water tank in the loft not being very high above the taps. Have a look in it in case a drowned rat is blocking the outlet.

Thanks JohnD
Removed the central screw (it was red hot too) but couldnt see/feel a screwdriver slot in there, tried various sizes but none really 'locked into place' enough to get any grip to try and turn it. Certainly wasnt moving freely, I think I was more likely to damage it that turn it.

Not got a large magnet so cant do the copper pipe test Im afraid.

There are 2 ancient isolators either side of the pump (top and bottom) that look like could use a radiator bleed key to turn? I isolated them both, opened centre screw again to let a bit of steam out til it stopped steaming, closed it again then opened the old isolators again, bottom one first. When I opened the top one, i think the pump made a noise, almost like a half hearted attempt to start (kinda like one of those friction powered toy cars when you pulled it back) but it only done it for a few seconds

 

[PullerGas]

No water or limited water in your C/Heating system. Check your F&E tank in the attic or if it's a sealed system, check the pressure gauge.
HTH

Thanks Puller, the smaller tank in the loft is about half full?

Ensure the tank inlet valve is free & running OK. Where the cold feed connects to the system, put a magnet onto the copper pipe there & if it sticks you've a blocked cold feed.
Or drain off some water from the system & ensure the F&E tank runs to top up the system water, if not you've a blocked cold feed or air lock.

Oh FFS don't turn these valves at the circulation pump they'll leak like a 3 month puppy!!
Happy to help.

 

[britishboy7]

Thanks again Puller
I was going to ask about draining off some of the water and where to do it from, guides Ive seen say theres a special tap at the lowest point of the system on ground floor but I've not found it. Once I've sorted the sticky/faulty pump I was going to add some Furnox F3 to the small tank in the loft but need to drain it down first before adding the F3 I think

 

[PullerGas]

The circulation pump may not be Friar Tuck'd, you may just not have water in the system.
You need to ensure there's water in the system before going any further.

 

[britishboy7]

The circulation pump may not be Friar Tuck'd, you may just not have water in the system.
You need to ensure there's water in the system before going any further.

And is that done by topping up the F&E tank? Excuse my simple questions

 

[PullerGas]

The circulation pump may not be Friar Tuck'd, you may just not have water in the system.
You need to ensure there's water in the system before going any further.

And is that done by topping up the F&E tank? Excuse my simple questions

No mate the mains cold water pressure inlet valve should fill the F&E tank.

 

[britishboy7]

Sorry Puller, I meant how do I ensure theres water in the system, as you advised? I meant do I top up the F&E tank to ensure there's (enough) water in the system or is there another way?

 

[JohnD]

Bleed the highest radiator in the house. Does water squirt out forcefully and without dying away?

If you have someone watching the f&e tank, when you draw water out, the ballvalve should open and top it up with the same amount. If water is not drawn from the f&e then the pipe is blocked.

You do not manually top up the f&e because it has a ballcock to supply it, like a WC cistern.

 

[britishboy7]

Bleed the highest radiator in the house. Does water squirt out forcefully and without dying away?

If you have someone watching the f&e tank, when you draw water out, the ballvalve should open and top it up with the same amount. If water is not drawn from the f&e then the pipe is blocked.

You do not manually top up the f&e because it has a ballcock to supply it, like a WC cistern.

Thanks JohnD, will try bleeding highest rad as soon as I get home, there are 6 rads on the 1st floor, how will I choose which to bleed of those?

Will opening a tap draw water eventually from the F&E tank?

I looked inside F&E tank yesterday and it is just over half full, I was assuming it would have more water in it? Ballcock looks OK as isn't submerged

 

[JohnD]

hot and cold taps have no effect on the f&e.

However a radiator drain cock will, and so will a bleeding screw, but more slowly.

The reason for trying the highest radiator in the house is that it will be more quickly apparent if the water level in the pipes drops when you drain some out, and the pressure falls away. This indicates that the feed is not working, most likely because it has been blocked with sediment in the pipe joint.

It would be helpful to scoop out the water and mud from the F&E and sponge it clean to avoid the mud flowing down into the pipework. If you tie up the float first, it will not refill the F&E until you untie the float. If water does not come out of the ballcock when the float arm goes down, the ballcock is faulty or perhaps someone has turned off a service valve in its supply pipe.
You can usually verify that a ballcock is working by pushing down on the float and seeing water squirt out, though sometimes the arm gets stuck. It is the same as in an old WC cistern.

The water level in the F&E only needs to be a couple of inches above the outlet pipe which is near the bottom. This allows more space for expansion when the system is hot.

 

[britishboy7]

Thanks again JohnD - quick update had Bgas round today and they replaced the CH pump and advised a powerflush, I've started a new thread asking about powerflushes, but thank you for your help over the weekend

Thanks again