I have de-sludged and drained down, and still have cold rads

[rickmd]

I have read so many posts here I thought it was time I wrote one.

I have a glow worm fuels saver F, open vented system, FE tank in loft, pump near immersion heater.

I have always had problems getting all the radiators hot in my house especially the 4 on the ground floor and the 1 in the basement. Recently I added de sludger and left it in for 10 days that drained the system from 3 drain points, and let cold water run through until it was clear. I then added inhibitor and limescale remover,but still its only the 4 rad upstairs that get hot.
I do have an immersion heater with a 3 way valve for hot water. There is also a stop cock type tap on one of the pipes near this 3 way valve. normally I have had it open, but last night I closed it and 2 of the rads on the ground floor went from cold to warm (not hot). Should this valve be open or shut.

Also I find I get a lot of hot water going into the FE tank, why is this.

I have my LSV's about a half turn open upstairs (where the pump is) and fully open downstairs (where the rads are cold)

Also I noticed the pump is not quite as quiet since I drained down

I have bled all rads and pump btw.

I have an boiler service due in 3 weeks, what questions should I ask the engineer. Im not convinced a powerflush is the answer should he recommend one.

Thanks Guys (and gals)

 

[footballfan]

your auto bypass valve (stopcock looking lever that you said) may not be set correctly and the water not getting to your affected rad(s).
it may be taking a short circuit (easier for it, less resistnace, etc).

maybe your cold feed tee piece is slightly blocked up, forcing water up and over your vent pipe.

 

[D_Hailsham]

Can you post a photo of the airing cupboard showing the HW cylinder, pump and all the other heating components there? A general view is better than close-ups of the individual components

 

[malkie]

What you closed sounds like your hot water flow circ,so you stopped the cylinder circs which allowed the heating to get full heat and not get robbed by the circs,also try lowering your pump as it is pushing up and over into the tank

 

[jobloggs]

Try turning off all your radiators except one and check if it gets hot especially at the bottom. If not you have sludged up pipe(s) which the desludger you mentioned didn't fix because it needs to flow to work.

Do this with each radiator in turn.

If each radiator get hot quickly when only it is on you may have a problem with the balancing of the rads between the different floors.

 

[sambotc]

Picture of controls would be good as suggested above. Could be the pump slowing down, not heating downstairs and if its not dissapating the heat may be going up the vent.

Does the boiler make any noise at all?

As above try turning off all the radiators except 1 of the downstairs rad's that dont get hot.


Sam

 

[rickmd]

I would have replied sooner, but obviously have not set up the alerts properly when people reply to my post.

I will get a photo posted

 

[rickmd]

Follow up since the plumber came.
He serviced my 20 year old boiler and said it was chugging along nicely, so I was able to ask him lots of questions about my cold rads. I explained that I had delsudged waited 2 weeks then added limescal remover and inhibitor. He believe that my problem is either..
a.) sludge and would require a powerflush, or
b.) air in the system.

Obviously the air problem is the first thing to look at as its free. The plumber told me to shut off the auto bypass (that i previously called the stop cock type tap that building regs now no longer allow people to fit as they are energy inefficient) and to shut of all the LSV's on each rad except one and make sure it heats up (which they all (but not at the same time) did, before i desludged). and to listen out for air bubbling up into the overflow into the FE tank. However if i do any of this, i just get the boiler boiling over into the FE tank but im not sure if its going up the vent pipe or the feed pipe, will need to check.

The boiler also cuts out all the time.

I cant see anyway of locating this air lock and getting rid of it. There also air in the pump, and I have removed the large screw cover on the front a few times but theres still air getting in, should i try setting the 3 way motorised valve to manual and then try bleeding the pump, theres definitely an issues with the pump as it make a sort of clicking noise since i drained down (its set to 2).

Will the problem resolve itself over time? or will I need to pay out for a power flush? Should I remove each offending rad and flush out?

Obviously when I drained the system I must have allowed a lot of air into it somewhere that now I cantget rid off. I can also sometimes hear the sound running water through the pipes.

 

[D_Hailsham]

PS Still no photos!

The plumber told me to shut off the auto bypass ... and to shut of all the LSV's on each rad except one and make sure it heats up (which they all (but not at the same time) did, before i desludged). and to listen out for air bubbling up into the overflow into the FE tank. However if i do any of this, i just get the boiler boiling over into the FE tank but im not sure if its going up the vent pipe or the feed pipe, will need to check.

What you plumber forgot to tell you is that, if you have only one rad open, you also need to temporarily set the pump to a lower speed to prevent pumping over (water going up the vent pipe into the F/E tank).

The boiler also cuts out all the time.

Do you mean when you have only one rad working? If so, this is not surprising as the boiler is overheating as the one rad is not able to cope with the heat produced by the boiler.

should i try setting the 3 way motorised valve to manual and then try bleeding the pump?

Yes, set the valve to manual so the CH path is open. Also do the bleeding when the water is cold. Have you checked the water levels in the F/E tank Should be about an inch above the outlet when cold. Make sure the bsll valve opens before the level gets down to the outlet, otherwise you could get air into the system.

Should I remove each offending rad and flush out?

Won't do any harm and is cheaper than a power flush - which can mean anything, take anything from an hour to a day and cost from £200 - £700 depending on who you use - and cost is no guarantee of effectiveness.

 

[Statia]

My folks have a Glow Worm Fuelsaver F which is over 20 years old too. They had problems with the boiler short cycling all the time, so we took the rads off and flushed them out with a hose in the garden, giving them a bash with a rubber hammer. Put them back on, Fernox cleaner in, run for a week, drain, fill, run until hot, drain, fill, run, drain etc. until the water ran clear when drained. Filled with inhibitor.

Job done. Nice piping hot rads, no short cycling.

 

[rickmd]

As requested here are the photos of my pipework, pump etc.

D_Hailsham, you said turn the 3 way valve to manual and bleed pump when water is cold. I did this and the pump sounded fine when cold water was running around, but once the water got hot it started making the clicking noise again so is it possible some air got pushed round into the pump again. It never seems to run smooth when the water is hot, only when cold.

I will turn all the radiators off bar one tomorrow and set the pump speed to 1 , to see if i can heat up the one rad. (the 4 upstairs are still working hot, its the 4 downstairs and one in basement where the boiler is that remain icy cold)

I dont undrstand the comment about the water in FE tank should be about an inch above outlet when cold, do you mean an inch below the overflow?, or do you really mean an inch above the feed pipe? if you mean above the feedpipe then ill need to bend the ball cock way down. As you can see from FE tank photo. In the photo of my pipework , label 1 is the vent pipe and label 2 is the feed. (There a valve in the feed pipe just before it goes into tank, could i try closing this to try forcing the water rounds rads, and pervent it from pumping over into FE?)

As you can see from the FE tank, water is cloudy, but i did desludge and drain from 3 points in the system.


To the previous poster, encouraging news re: flushing rads, i will try this when kids and wife allow me to.

boiler

• rickmd
• 22 Nov 2008
• 1

FE tank

• rickmd
• 22 Nov 2008
• 1

 

[D_Hailsham]

I dont undrstand the comment about the water in FE tank should be about an inch above outlet when cold, do you mean an inch below the overflow?, or do you really mean an inch above the feed pipe? if you mean above the feedpipe then ill need to bend the ball cock way down. As you can see from FE tank photo. In the photo of my pipework , label 1 is the vent pipe and label 2 is the feed. (There a valve in the feed pipe just before it goes into tank, could i try closing this to try forcing the water rounds rads, and pervent it from pumping over into FE?)

Sorry for the confusion, I meant one inch above the feed pipe, i.e the outlet to the CH; the other "outlet" is always called the overflow. Bend the arm to lower the level.

Do not under any circumstances close the valve. If you do there will be nowhere for the water to go when it expands on heating, except up the vent pipe and back into the F/E tank. The F/E tank level will rise, as expected. But when the heating cools down the water level will not drop as the water cannot get back into the system. Instead air will enter the system via the vent pipe - which you are trying to avoid!

D_Hailsham, you said turn the 3 way valve to manual and bleed pump when water is cold. I did this and the pump sounded fine when cold water was running around, but once the water got hot it started making the clicking noise again so is it possible some air got pushed round into the pump again. It never seems to run smooth when the water is hot, only when cold.

Just to clear up any more confusion, was the pump running when you bled the radiators? It should not be running.

I will turn all the radiators off bar one tomorrow and set the pump speed to 1 , to see if i can heat up the one rad. (the 4 upstairs are still working hot, its the 4 downstairs and one in basement where the boiler is that remain icy cold)

No need to leave the boiler running to long. All you are trying to check is that water can flow through each rad and that the rad gets hot. This confirms that the path from boiler to rad and back to boiler is clear.

I take it that the Hot water tank etc in the photo is on the first floor, where the hot rads are. These rad will therefore be nearest the pump and will need the lockshield valve closed more than the rads downstairs and in the cellar.

 

[rickmd]

Do not under any circumstances close the valve. If you do there will be nowhere for the water to go when it expands on heating, except up the vent pipe and back into the F/E tank. The F/E tank level will rise, as expected. But when the heating cools down the water level will not drop as the water cannot get back into the system. Instead air will enter the system via the vent pipe - which you are trying to avoid!

ok understood, and in the FE tank I will bend ball cock arm down to restrict water level to 1 inch above the feed

Just to clear up any more confusion, was the pump running when you bled the radiators? It should not be running.

no the pump was not running when i bled it, i simply unscrewed the silver screw until water dribbled out, i collected about 20 cl before tightening up again. Like I say it was quite for a minute or so running on cold, but when the water got hot the pump became noisy again.

No need to leave the boiler running to long. All you are trying to check is that water can flow through each rad and that the rad gets hot. This confirms that the path from boiler to rad and back to boiler is clear.

OK, i didnt get to try that today, but will do very soon, is there any particular radiator i should try first?

I take it that the Hot water tank etc in the photo is on the first floor, where the hot rads are. These rad will therefore be nearest the pump and will need the lockshield valve closed more than the rads downstairs and in the cellar.

Thats right, water tank is on 1st floor with pump and the hot rads. The first floor rads LSV's have always been opened just enough to get a flow, id say about 1/8 to 1/4 turn open.

Dumb question but can you tell me which way the flow would be going from the pump, i presume its going upwards.

 

[D_Hailsham]

Just to clear up any more confusion, was the pump running when you bled the radiators? It should not be running.

no the pump was not running when i bled it, i simply unscrewed the silver screw until water dribbled out, i collected about 20 cl before tightening up again.

If you read my question carefully, I asked if the pump was running when you bled the radiators.

No need to leave the boiler running to long. All you are trying to check is that water can flow through each rad and that the rad gets hot. This confirms that the path from boiler to rad and back to boiler is clear.

OK, i didnt get to try that today, but will do very soon, is there any particular radiator i should try first?

Might be a good idea to start with the rads on the first floor, then ground, then basement. Work away from the pump.

The first floor rads LSV's have always been opened just enough to get a flow, id say about 1/8 to 1/4 turn open.

That sounds about right.

Dumb question but can you tell me which way the flow would be going from the pump, i presume its going upwards.

I hope not! The layout of your system means that the pump should be pumping downwards. There will be an arrow on the side of the pump showing flow direction.

However, Grundfos say this about installation:

It is preferable to install Grundfos circulators in a vertical pipe pumping upwards. This position ensures that the pump shaft is horizontal, which reduces the thrust bearing load and ensures positive air purging from both the rotor chamber and impeller housing.

Pumping downwards in a vertical pipe is not recommended as this may lead to air locking of the pump, with resultant loss of performance. However, pumping downwards is acceptable provided an effective air vent is incorporated in the system, before the pump.

May be this is the cause of your problem and the noisy pump. However, it is not just a case of turning the pump round, the pipe work would have to be altered to make sure the feed and vent pipes (1 and 2 in your pics) were still on the inlet side of the pump.

 

[rickmd]

[quote="D_Hailsham"Just to clear up any more confusion, was the pump running when you bled the radiators? It should not be running.
[/quote]
I bled the radiators when the pump was not running , but no air came out of any of them.

I also emptied a bucket full of water from the FE tank and bent the float down so water level is now about 1 or 2 inches above the feed.

No need to leave the boiler running to long. All you are trying to check is that water can flow through each rad and that the rad gets hot. This confirms that the path from boiler to rad and back to boiler is clear.

i have just turned off all rads, i closed TRV and LSV on each, leaving one open on the ground floor. There was a lot of gurgling and big knock and a rush of hot water up the vent pipe and into the FE tank. I did this to all 5 offending radiators but none of them even got warm.
I didnt start on the first floor by the way, as all these rads get piping hot so assumed there was no block or air there. (plus i didnt have much time)

The layout of your system means that the pump should be pumping downwards. There will be an arrow on the side of the pump showing flow direction.

It is pumping downwards, and the vent and FE pipe are above the pump on the inlet side.

When closing of all the rads except one, there were various noises, and the pump went quite then loud, i could also hear what sounded like running water in the pipes. It really does sound like there is air in the system, but I cant get it out. I will try bleeing again tomorrow once the system has gone cold.