Potterton Kingfisher 2 RS 100

[Johnysmall]

I went to a house this afternoon to look at a leaky wc. Whilst there the fella told me he had a problem with the heating.

I'm a bit out of touch heating wise, heres the situation.

500 year old cottage, 10 year old extension, 5 bedrooms, 19 radiators. pumped (15-60), floorstanding balanced flue kingfisher boiler, unvented hot water. 50/50 old rads/new rads, TRV's each rad, programmer, roomstat.

He says when he puts heating on the boiler fires up and seems ok but all the rads on one side of the house (5) dont get hot (or warm even). These rads are the furthest away from the boiler. After a while (assume when most rads reach temperature) the boiler turns off. The boiler will not fire back up again unless he switches the programmer off then back on again. When the temp drops the stat clicks but it still doesn't fire up.
The pump works ok, as do the motorized valves.

Is this more than likely the boilers not big enough (26kw) struggling to reach the furthermost rads, or something more sinister??


Thanks in advance.

 

[gas4you]

Has he tried turning off all the rads that do work and the hw? See if those other rads get hot then.

Are these rads on a seperate zone?

Could be pump 'appears' to be circulating but actually isn't.

Could be a balancing problem, or could be sludge in the system.

The on/off problem with the programmer could be a sticking zone valve. Do you mean the room stat clicking back on or the boiler stat?

 

[Johnysmall]

Has he tried turning off all the rads that do work and the hw? See if those other rads get hot then.

Yes first thing I said, he has and it works.

Are these rads on a seperate zone?

It's Y plan 2 x 2 port valves,, 1-HW 1-rads

Could be pump 'appears' to be circulating but actually isn't.

Pump is circulating took screw out and used my pump circulating detection probe (flathead)

Could be a balancing problem, or could be sludge in the system.

The 'old' rads are only getting hot at the bottom.

The on/off problem with the programmer could be a sticking zone valve. Do you mean the room stat clicking back on or the boiler stat?

I think he means the room stat, he said when the boiler stops after a while he hears the click of the stat and the boiler does not fire up again

Do you think the boiler is ok to supply that many rads?

 

[gas4you]

Rads getting hot at bottom is air in the system usually, cold at bottom, hot at top = sludge build up.

2 x 2 port valves = S plan

I've had many a pump that were spinning as in your test but not circulating. I always quickly swap a new pump on to test.

If the 5 rads are getting hot when others are off it still could be muck in the system, or at worst the pipe sizing is totally wrong so not letting enough water to the rads quick enough. Water will always find the easiest route, hence balancing.

 

[Gasguru]

Probably just full of air and poorly balanced.

Depending on the pipework layout and with 19 rads balancing can be tricky. It will take several attempts to get it spot on.

 

[Johnysmall]

Rads getting hot at bottom is air in the system usually, cold at bottom, hot at top = sludge build up.

2 x 2 port valves = S plan
Cant believe I posted that......what a knob


I've had many a pump that were spinning as in your test but not circulating. I always quickly swap a new pump on to test.

just remembered, he said when he switches the power off to the pump, he can hear water gushing down the pipes

If the 5 rads are getting hot when others are off it still could be muck in the system, or at worst the pipe sizing is totally wrong so not letting enough water to the rads quick enough. Water will always find the easiest route, hence balancing.

BTW I opened the manual air vent on the flow just before it enters the cylinder and there was no air or water. the hot water is fine, flow and return both piping hot on entry and exit of the cylinder

 

[gas4you]

Ah, now it sounds like there is a blockage in the cold feed, at the t where it joinds the heating pipe work, but just check there is water in the f&e tank first.

If there is a blockage it will need to be cut out and pipe work replaced.

Very common on old open vent systems

 

[Johnysmall]

Ah, now it sounds like there is a blockage in the cold feed, at the t where it joinds the heating pipe work, but just check there is water in the f&e tank first.

If there is a blockage it will need to be cut out and pipe work replaced.

Very common on old open vent systems

Thank you very much