Central Heating performing erratically *Warning Long Post*

[antomac1001]

 

[petit_pablo]

My thoughts
I’m thinking – sludgy system and/or a dying pump

Cant believe i read most of that.

In short you have a circulation issue. You could try a sludge remover but if there isnt any circulation its effectiveness is limited. It would be worth trying the pump to see if it makes a difference 1st.

Otherwise a decent flush is probably a good idea.

 

[antomac1001]

Thanks petit-pablo. Srry about your eyesight though - bet you look like this now

I will have a ring round to see the cost of getting a new pump fitted. How much do you think that job would cost if i supplied the new pump (an exact copy of the old one)?

 

[antomac1001]

I tried to anticpate what questions would be asked when I provided the details of the problem - ergo the long post. I thought this might be better than batting back/forward of questions and answers. Thanks anyway

 

[Chudley]

I assume your radiators are properly balanced (i.e. via the lockshield valve on each radiators)?

 

[jon26]

Background
Hi guys - I have scoured the forums for an exact match to the problems I have with my CH system, before posting as a new topic, but I have only found some topics with some similar problems. This gas CH and HW system operated without problems until last year when it was found that the Glow worm Micron 50FF boiler needed a new circuit-board. The circuit board was duly replaced. In the process of investigating that problem some dark water ran from the pump when the center screw was removed. Now some nine months later there are multiple symptoms. In it’s six years of operation it has never been fully serviced but now it’s my problem as the previous owners have so kindly informed me. This is probably the longest post on DIYNOT but I wanted to try to provide the fullest possible picture. I have zero plumbing experience and only know the terminology from reading posts to this forum but I am sure that I have applied all the terms correctly.

The system – Natural Gas – open vented with F&E tank in loft
Rads – 3 double sided about 3 ft long, 2 single sided 2 ½ ft long. Main rad in living room has no TRV. Honeywell Stat Controller mounted in living room. Boiler is Glow Worm Micro 50FF. System has Honeywell smartfit base unit and 2 smartfit motorized valves. Pump is a WILO Gold 50. Pump, actuators and cylinder have cables to the base unit.

Symptoms
HW goes on when called. CH wont go on when called with HW. Also CH only comes on enough to heat either two rads upstairs (which is just enough not to freeze to death as it happens) OR to heat the main rad in the living room. So we have been anticipating when we go to bed and sending the heat upstairs accordingly.

Observations
· Two rads (Bedroom and Bathroom) get warm enough during the night as called for by the controller according to automatic settings (3 on/off daily settings available) – as long as all other rads TRVs are in the closed position and the CH is set to MAX and the two rads mentioned have their TRVs Except for the L.Room rad which hasn’t got a TRV but which seems to lose it’s “priority” once any upstairs rads are open/on.
· Pipes leading to the airing cupboard where the actuators and pump are from the boiler will burn if touched after the boiler has been on for some time.
· Each of the actuators moves to ‘vent’ when called using the controller (is this normal?) BUT the pointer will not move across fully to the ‘B’ position – it stops a full centimeter short. At 12 noon each day both actuators move in sequence fully to the ‘vent’ B’ position then back to ‘fill’ A’ then back to their original position.
· The boiler will switch off before rads are warm (I assume to protect itself)
· Boiler will switch on for less than one minute many times once pipework becomes burny hot.
· The 22mm pipes leading from the boiler into the airing cupboard become very hot when either HW or CH is called on the controller but this is not translated to the rads.
· There is a constant roaring when the CH is on. It’s so loud that you might think there was a great furnace in use instead of the pithy heat that is in evidence. This roar seems to have no single point of origin – it is throughout the pipe work. The roar increases/decreases as the pump selector switch is moved from I to III and vice versa but when you listen close to he pump, the pump or movement within it is pretty quiet.
· The tank in the airing never gets hot when CH is on. I can touch it even when CH has been on for hours - is this normal?
· Adjusting the pump speed has no discernible effect on the speed that rads get warm or temperature of them.

Actions
· Some time ago a friend opened the pump ( WILO - GOLD 50 ) screw and murky water came out but I assumed this was brown water that we sometimes get in our drinking water. Yesterday I opened the pump screw and water trickled out. With the pump on I turned the speed to I then II then III and each time I inserted (gently) a screwdriver. I could feel something like a cog wheel turning so I assumed the pump is working – is that the case?
· I have bled all the rads using the radiator key but only water trickles out.
· I have inspected the F & E tank in the loft. It has a small amount of water in it when when the system is cold and the volume increases the longer the CH is on. Depressing the ball cause a steady flow of clean new water. The F & E tank is insulated and frost proof with a lid but the water within has an oily rainbow surface. There is a tide mark, which I assume is the usual expansion level but the mark is about 1 inch high of bright reddish-brown silt like material.
· I have used a small magnet in various places on the system - I was told this might show signs of corrosion/magnetite. The magnet failed to 'stick' anywhere. (Okay – don’t laugh…but tomorrow I am buying a left handed screwdriver)
· I used the drain cock on the kitchen rad to drain a litre or so of water from the rad to check the colour, consistency etc. The water was clear-ish with a tinge of brown. Does this say anything about the system?



To give you an idea whats happening - after 2 hours of operation with CH on at the controller and set to MAX (30oC), pump set to MAX and ALL TRVs set to OPEN - only two rads show heat. These are the two that are usually on throughout the night. Their flow/feed pipes get scalding hot. All TRVs have bi-directional valve bodies. Nowhere else is getting heat - even the feed pipes on all other rads are stone cold. The rad in the bedroom that houses the airing cupboard/cylider/pump doesn’t even heat up.

My thoughts
I’m thinking – sludgy system and/or a dying pump but would the pump still try to bite the screwdriver when I insert it in the center screw hole if it wasn’t working? How can I test for sludge if the pump water runs clean when the screw is removed and the water that runs from the drain cock on the rad in the kitchen is only slightly tinged brown?

The boiler can take up to ten minutes before sparking up (i.e. the burner light coming on) from cold. Could there be a problem with the gas supply even?

I have drawn a picture of the airing cupboards plumbing – Red indicates the pipework that gets scalding hot when HW or CH is selected at the controller, blue pipes stay cold.

You really should get out more

 

[Gas2Air]

Ha Jon that made me laugh out loud. Sh't maybe i should get out more?

 

[antomac1001]

Thanks for the reply chudley -

Anyway - the radiators lock shields have not been touched since installation (they were balanced then).

Is balancing an ongoing thing?

 

[Agile]

The balance settings will change as the rads become differentially sludged up.

However the solution is to clear the sludge and not to rebalance.

Tony

 

[antomac1001]

Thanks Agile, thanks.

Can I ask one more thing of you? I inserted a screwdriver gently into the pump when it was on, at the centre screw hole and I felt a ratcheting - as if the tip of the screwdriver was grating against spinning cog teeth. Does this mean the pump is definitely working and at least trying to pump?

 

[D_Hailsham]

Deleted!

 

[Agile]

It means the pump is turning, no more and no less !

Tony