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Hi All,

On Thursday there was a water leake a few steets away from us And we had no water most of the day.

About 10 minutes before my neigbour said the water supply was back on I remember hearing a fair amount of activity from our airing cupboard. I took this as water/air moving through as the supply/pressure was recaps being restored (it was partially, then fully)

The leak was fixed and all seemed ok but in the evening I notice the hot water was not clean. It was brown tinged and although I am not sure I thought I could smell a chemical smell.

I continued to run hot water off until it was clear.

Unsure if the coil had split I turned off the demand for hot water and left for the plumber to see the following day. I had manually twisted the presure relief above the cyclinder, which let some flow down the tundish, and I then checked if the system needs refil through the filling loop (it did a little At least but it is hard to gauge how much)

Just before the plumber came we noted the downstairs overflow bhind the toilet cistern was dripping and had been for some time (It still is)

the plumber thought the coild was fine and the dirty hot water was due to the the water supply and pressure being restore to the hot water cyclinder i.e. 20 years debris and crud distrubed at the bottom of the cyclinder. The reason for the drip because the pressure relief valve has a fault (because Ive touched it) orig isnt seating correctly perhaps with debris (assumably as the mains cold migh not have been clear itself once restored. The central heating had been on a couple of times since a filled and boilder pressure seemed normal (another reason he doesn’t think it was the coi)

he left and gave me his phone number but advised to run a few hot water baths to clean things out, and to call him this week if the drip hasn’t stopped.


Over the last two days I have rup about 10 baths full baths. not hot water bath has been clear, but the following cold one (from the refill afterwards the water is clear.

Anyway 10 baths later the water still isnt clear (only the ones run directly after the hot one).

Ive been watching the pressure gauge on the boiler and this hasn’t seemed abnormal to me i.e 1.5-2 bar when hot, 1-1.5 bar when cold, I have refilled using the filling loop throughout

I cant say I have left the cyclinder cold and then seen if several hours later it has gone dirty, I will try that next

Is this sounding like the coil, or just distribution of the dirt/silt at the base fo the tank. I cant figure out if it is the hot water cyclinder is clearing, or the dirty water from the central heating system is slowly being diluted and cleared from the hot water cyclinder! To me I’m thinking cyclinder because after running a dirty bath off from the cyclinder the next one straight away is clear and hasn’t had time to take get dirty from the water from the split coil.



Any thoughts or help would be very much appreciated.
 
Normal as the water board doesn’t flush the lines out after work has been done always best to run a cold tap for around 10-15mins afterwards

you would be the other way round eg clean water going into the heating system as the unvented is a higher pressure than the heating system
 
also pressure would increase in the boiler as stated above the pressure in the cylinder is greater than the system pressure
 
you would be the other way round eg clean water going into the heating system as the unvented is a higher pressure than the heating system
Yes I would expect that, but also by the same principle the dirty water from the heating system (assuming the coil did split/perforated) would also come into the tank.

Baths filled from the tank are not clear water when its been in the tank for a while or the hot tank has been heated from the central heating system. if the tank is emptied immediatly emptied immediately after the water is clear.

If the the main water supply coming back on had stirred up the tank, surely that second flush out would be dirty too.

I come back to empty the tank after a few hours and it is dirty again.

Surely after a dozen full baths (to overflow) if the tanke was dirty from stirring up, or dirty water coming in once the leak in our neighbouring street was fixed , surely it would be clean by now.

I have been watching the pressure gauge all weekend, cant say I’ve noticed an general increase or decrease
 
Here are some pictures

on the first night notice, i rant the hot water tank out, after a n hour going from this to clear
IMG_1641.jpeg
 
I just feel like I could be slowly replacing the dirty central heating system with clear water from tank refills, and this isnt the behaviour of the coil being intact and slowly flushing the hot water tank clear.
 
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Nope that’s water board dirty water
 
Ok. Thought I feel like I’ve smelt chemicals when it was at its strongest. Dirty boardwater have a smell?

Can I ask how you can tell the difference between dirty board water and radiator water?

And why would the tank keep filling and then running clear. the cold supply from the water board is running clear now, and has been for three days, so if this is dirty board water in the system how many tank full do I need to clear it. 13 bath fulls i.e 13 full tank empties and refills And still going
 
Yes as they’ve probably cleaned the pipes

radiator water will be black

your cylinder is full would get the plumber back to drain it and refill
 
Yes as they’ve probably cleaned the pipes

radiator water will be black

your cylinder is full would get the plumber back to drain it and refill
When you say cylinder is full you mean full of crap? By drain it and refill do you mean more a back wash to clear it out.

I feel I have already been draining and refilling it about 13 times. Same hot water tank (150 litre I think mine is) fills the bath with hot water (all those dirty bath picture are hot water) and is running cold by the end (so I feel the tank is emptied each time, apprecaite it is refilling as it empties mind
 
Yes you won’t fully empty the cylinder

also did you have a letter off the water board stating there going to be doing work etc ?

you can phone them up and request a visit from one of there engineers as you’ve got discoloured water since they’ve done the works
 
Yes you won’t fully empty the cylinder

also did you have a letter off the water board stating there going to be doing work etc ?

you can phone them up and request a visit from one of there engineers as you’ve got discoloured water since they’ve done the works
No letter. As I think I said in my first post, there was a leak a few streets down the hill which affected our supply (it was leaking up through their pavement). And when it can back on there was a lot of noises from the tank/airing cupboard (air and water sounds not clunking sounds)
 
Change the cylinder if you want to, but if the coil had gone your heating would be at the same pressure as your cold main so the gauge would be over 3 bar all the time and your boiler PRV would be passing water all the time.
 
Change the cylinder if you want to, but if the coil had gone your heating would be at the same pressure as your cold main so the gauge would be over 3 bar all the time and your boiler PRV would be passing water all the time.
Ok, thanks. Boiler gauge hugs 2bar at times but not seen go higher last
Few days

is a tank flushing the only way im
Going to clear the water? I guess if the coil hasnt gone there is no real worry, it’s just a Little dirty and will eventually clear/settle down?

As mentioned in the original post
I do have a drip from (I assume) a PRV flowing through the tundishh and out to a drip outside external to the downstairs toilet. I had read that was a symptom of a broken coil. Any idea what the cause of that might be? Thanks.
 
So there has been some developments.

Last tuesday I flushed the tank out with a hose from the drain out point to outside, several times over (fresh water to the tank isolated), hot tap open to vent it, blasted with cold water when empty to clear any sediment at the bottom of the tank assuming this is the issue that has been suggested (On here and by my local plumber).

I closed the tank drain valve, and left the tank empty for several hours to watch for a pressure change on the boiler. It Dropped about 0.2 bar over the 5 hours in the afternoon to evening. Put this down to a natural loss from the system still cooling from the heating on in the morning, and the day/house getting cooler.

Hot bath water still wasnt clean but better, so continued with tank flushing the next day. Even tried a back flush but only at mains pressure. With the tanke empty, this time left a tub under the tank drain point, and left the drain valve open. My thoughts were if the coil was split, surely it would be pi$$ing out water into the empty tank. An hour passed, not a drip or the sound of one in the tank.

Next day hot water was clean, finally and end to this. Seemed it was just dirty water from after the nearby street water leak and sediment stirred from the bottom of the tank. We have all showered and our little one bathed in it twice. The central heating has been on and off throughout, but not as much as weather is getting milder. We still have a drip from our overflow pipe downstairs but myself and plumber put this down to the cold pressure relief valve not re-seating after I clicked it over (probably the first time in 20 years).

Anyway..... 5 days on, tonight run a bath and get this below

Pressure at the boiler was a little low at just less than 1 bar with heating off but hot water on. Opened the filling loop and it immediately jumped 0.5 bar.

So. All things considered. Is this still dirty mains water, sediment stirred after numberous tank drains. Or is it the coil.

Any help would really really be appreciated.
 

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Change the cylinder if you want to, but if the coil had gone your heating would be at the same pressure as your cold main so the gauge would be over 3 bar all the time and your boiler PRV would be passing water all the time.
PRV as been passing water, hence the constant drip/trickle out to the overflow downstairs.

but pressure at the boiler gauge seems to have gone down a bit after several days and as per my previous post, opening the filling loop it went up by 0.5 bar in seconds
 
I would ring the water board and check there still not doing work in the area as they could be replacing water mains etc
 
I would ring the water board and check there still not doing work in the area as they could be replacing water mains etc
Thanks for your reply. There are no issues registered in the area on united utilities, but I will ring them.

what I don’t get about the posts on here about dirty mains water is I have drained down the tank and tried to flush it tank, several times. Each time it being filled with fresh cold water which is coming into the house clean....... but the water is coming out of the tank dirty when it’s left in their any given time.
 
Just drained out the hot water tank. For info central Heating went off about 90 minutes ago hot water about 50 minutes ago.

It took about 30 minutes to empty the hot water tank/cylinder meanwhile the gauge on the boiler has dropped from abou 1.3 bar to about 0.4 bar.

still just dirty mains water?
 
Gauge pics
 

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I'd be wanting to pressure test the coil at this point, to be certain what is going on. More simply, while the boiler is cold and the cylinder is empty, if you top the pressure back up to 1 bar, does it drop again?

It has been suggested by others that if the cylinder were leaking into the primary circuit (boiler water), the pressure would be over 3 bar and the PRV (on the boiler) would blow. But we don't know what the OP's mains pressure is: it might not even be as high as 3 bar (can be as little as 0.7 Bar).

Also, could the OP please run a bathful of COLD water? This would give us an idea of the quality of the mains water entering the house.
 
I'd be wanting to pressure test the coil at this point, to be certain what is going on. More simply, while the boiler is cold and the cylinder is empty, if you top the pressure back up to 1 bar, does it drop again?

It has been suggested by others that if the cylinder were leaking into the primary circuit (boiler water), the pressure would be over 3 bar and the PRV would blow. But we don't know what the OP's mains pressure is: it might not even be as high as 3 bar (can be as little as 0.7 Bar).

Also, could the OP please run a bathful of COLD water? This would give us an idea of the quality of the mains water entering the house.
Thanks for your reply Ric2013.

That is the thing that confuses me. Couple of people on have said the boilder pressure increase if the coil was perforated in the unvented indirect hot water cyclinder/tank. Two local plumbers Ive spoke to have suggest it would decrease.

cold water bath picture just run attached
 

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Couple of people on have said the boilder pressure increase if the coil was perforated in the unvented indirect hot water cyclinder/tank. Two local plumbers Ive spoke to have suggest it would decrease.

There are (at least) two types of leak with different behaviours.

Most of the discussion in this thread assumes a simple bidirectional leak, such as one caused by pin-hole corrosion or a split in copper tube. The flow through such a leak depends on the pressure difference in a symmetric manner. I.e. positive difference causes flow in one direction. Reversing the pressure difference causes flow in another direction.

The second type of leak occurs when joint (solder or welded) fractures but is held normally closed by the springiness of the metal pieces being joined. Such a leak can exhibit unidirectional, aka 'diode', action. I.e. allow flow in one direction, in this case from CH to DHW, but not vice versa.

The second type is less common than the first type and can give rise to some puzzling behaviours.

Anyway, I suspect you have a 'second type' of leak. To diagnose, you either need to put tracer dye into the CH water or pressure test the cylinder coil.
 
Thanks Chuck, thats interesting thoughts. It doing my head in!

Afte a bit of a tank refill and emptying again I feel like it should be empty now but its still draing with not quite clear water and a very slight noticeable chemical film on the stop of the water.

Getting noises as it goes. Is this the sound of the coil draining into the tank?


Pressure has continued to drop at the boiler thought slowly. Down from 0.4 bar earlier to just over 0.2
 

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Fill the boiler up to 1 bar once the cylinder has stopped draining does the cylinder start running with water
 
Fill the boiler up to 1 bar once the cylinder has stopped draining does the cylinder start running with water
Thanks.

Currently the cyclinder is still running at a slow pace into the washing up bowl which I keep emptying. Water slightly browned.

To fill up the boiler I guess I just need to open the cold water isolation above the tank (which will fill the tank again) but t will also provide water to the filling loop which is above the tanke (which I need to use to raise the boiler to 1 bar) Is that right?
 
Have you got a pic ?
 
Currently the cyclinder is still running at a slow pace into the washing up bowl which I keep emptying.
Open a hot water tap to allow air in and help drain the pipework. (The glugging sound on the video is the clue that this is needed.)
 

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