Central Heating Problems

[richard001]

Good afternoon all, I have a few problems with my central heating / hot water system and require a lot of help to find a solution.
We have an old Apollo Fanfare 30/50 wall mounted boiler. Last year 29/6/04 we had a new Grundfos Selectric 15/50 pump fitted as it was leaking and the system was treated with Fernox.
Recently the boiler and the radiators have been clanging and banging a lot. Have bled all radiators except one (bleed nipple was broken) this solved the banging for a few days, but then came back. Have bled the radiators a couple of times since, but they still keep getting air in them.
At present, the grundfos pump above the boiler is getting hot to the touch. (It is on setting one, was on setting 3), the boiler sounds like its kettling and some of the rads get hot when only on hot water.
Have spoken to a number of people who have said that it could be the motorised valve (3 port 22mm Honeywell) not functioning. Others have said its down to air getting into the system. The valve on one of the rads when i turned it off started leaking, so have opened it a little and now doesn't leak, but there is a circle of water around the top of the valve, this is the rad with the broken bleed nipple.
If I replace the rad and valve, (think the leaking valve is dragging the air in) will this stop the air getting into the system? or any other suggestions.
Perhaps its the motorised valve, dragging in the air!
Also why is the grundfos pump getting hot...
Any suggestions or comments on how to correct the problem and the best ways to do it would be greatly appreciated.
Regards
Rik.

 

[B.O.B DOLE]

Good afternoon all, I have a few problems with my central heating / hot water system and require a lot of help to find a solution.
We have an old Apollo Fanfare 30/50 wall mounted boiler. Last year 29/6/04 we had a new Grundfos Selectric 15/50 pump fitted as it was leaking and the system was treated with Fernox.
Recently the boiler and the radiators have been clanging and banging a lot. Have bled all radiators except one (bleed nipple was broken) this solved the banging for a few days, but then came back. Have bled the radiators a couple of times since, but they still keep getting air in them.
At present, the grundfos pump above the boiler is getting hot to the touch. (It is on setting one, was on setting 3), the boiler sounds like its kettling and some of the rads get hot when only on hot water.
Have spoken to a number of people who have said that it could be the motorised valve (3 port 22mm Honeywell) not functioning. Others have said its down to air getting into the system. The valve on one of the rads when i turned it off started leaking, so have opened it a little and now doesn't leak, but there is a circle of water around the top of the valve, this is the rad with the broken bleed nipple.
If I replace the rad and valve, (think the leaking valve is dragging the air in) will this stop the air getting into the system? or any other suggestions.
Perhaps its the motorised valve, dragging in the air!
Also why is the grundfos pump getting hot...
Any suggestions or comments on how to correct the problem and the best ways to do it would be greatly appreciated.
Regards
Rik.

have you checked the ballcock in the expansion vessel is not sticking

 

[oilman]

Drain a bucketful of water from one of the drain cocks. If you can't get water out, you have a blockage in the feed.

Though you have not said if it is an unvented system.

 

[doitall]

First thing to check is the rad with the broken air vent, if this is full of air then the rad will corrode, your problem could then be Hydrogen and not air.

 

[kevplumb]

have you checked the ballcock in the expansion vessel is not sticking

 

[richard001]

To all, thanks for your comments so far.

The system has an expansion tank in the loft. Does this mean it is vented?
If not, how do i tell if it is vented or unvented?

The rad with the dodgy valve makes a lot of noise, but as the bleed nipple is broken I cannot bleed hence the plan to change the rad. I assume it is full of air/something.

I will attempt to drain off a bucket of water, from the tap by one of the groundfloor rads and let you know what happens

I will check the ballcock in the expansion tank and let you know its condition and the condition of the water in the tank.

Cheers

Richard

 

[ollski]

could be the pump was fitted the wrong way round or simply a more powerful pump and not enough head of water.Usually if you can bleed the rads without the air pressure dropping it won't be blocked. (depends how much air you're bleeding of course)
For the rad valve just unscrew the top nut round the spindle, take it off and roll a bit of ptfe tape into a snake shape. make a circle out of your ptfe and put it down the bottom of the valve under where you took the nut out then put it back together. That will reseal the packing gland.

 

[Agile]

I do have to say that I would put my money on a blocked feed pipe.

As this may not be immediately obvious to a non professional a possible temporary solution and confirmation of the problem will be to introduce water into the vent pipe above the expansion tank.

If youu can do this, often with a funnel and rubber tubing to push around the bend, then the level in the expansion tank will rise if its not blocked.

If it is blocked then the added water will give a temporary solution until you replace the blocked pipe.

Tony Glazier

 

[richard001]

To all, current update on the information obtained so far.

The drain cock when opened flows freely, with no apparent spluttering. Took about 3 seconds for the water to start to flow. The water is not clear, slightly cloudy with bubbles and there is a small quantity of black deposits in the water.
The water level in the expansion tank dropped and started to fill itself slowly.
The motion of the ball cock does not appear to be sticking, but when the ball cock shuts itself off, it continues trickling for a period.
The expansion tank, has an overflow pipe, inlet pipe (through the ball cock) and outlet pipe. There is also a pipe which comes from another source and loops over the top of the tank and down into it. (Stopping above water level) I assume this is the vent. Is this right?
The expansion tank is only about half full of water. Should it contain more? if so I will try the rubber pipe method into the vent pipe and fill the water level up thay way in order to make the other checks.

With regard to the valve, do i have to drain the system, or if i close the other valve off and then start to dismantle the leaky one will I be OK, or will i flood the kitchen. Since the bleed nipple is broken on the rad, will it just be better to change the rad and the valve in one go? I assume the system will have to be drained to allow me to do this. When refilling the system what inhibitors etc would you recommend adding to the expansion tank to help improve the life of the system.

Thanks for your help so far, it is greatly appreciated.

I will await a response and then, make any further checks/post comments accordingly.

Best regards

Rik

 

[kevplumb]

The expansion tank is only about half full of water. Should it contain more? if so I will try the rubber pipe method into the vent pipe and fill the water level up thay way in order to make the other checks.

no leave it alone

as for the rad change the rad personally i would change the valves as well

which comes from another source and loops over the top of the tank and down into it. (Stopping above water level) I assume this is the vent. Is this right?

yes

sentinel x 400 cleaner leave it in a couple of weeks

 

[Slugbabydotcom]

Sounds like the by pass needs opening a bit to me. Has someone turned it to the closed position?

 

[namsag]

apollo is low water content boiler so grunfoss 15/50 should be set on speed 3 very rarely you can have it on a lower speed without creating noise

 

[richard001]

To all, once again many thanks for your comments.

I will:

leave the expansion tank alone.
change the radiator and the valve
set the pump back to speed 3
add cleaner when I change the radiator

What/where is the by pass? and how do you turn it on/off?

I am still concerned about the pump casing getting hot. How hot should it get?

When the Fernox was introduced to the system, when the original pump was changed should it have been removed after a couple of weeks as well?
Nothing was mentioned to us about this so it is still in the system to my knowledge.

To remove the cleaner I assume the system has to be drained and refilled?

Can the gate valves either side of the pump be used to bleed air from the system?

Best regards

Richard

 

[gazthepottertonengineer]

pump will get very hot as the water its circulating will be about 80 degrees

 

[gazthepottertonengineer]

and no gate valves either side of pump are to isolate water so you can change pump only and the sentinel he put in wouldnt need to be drained out as its inhibitor not cleanser which would need draining out after 1 week or so