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Blocked heating pipe

Does what it says on the tin
staffordian
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Re: Blocked heating pipe

#3369

Postby staffordian » November 10th, 2016, 5:01 pm

Im not sure if its relevent, but do you happen to know if the pipes are normal (half inch or so diameter) or microbore?

I just imagine microbore pipes might be trickier to clear or at least need a different approach.

Staffordian

IsleofWightPete
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Re: Blocked heating pipe

#4093

Postby IsleofWightPete » November 12th, 2016, 10:55 am

[quote="Jimarilo"]The first thing I would is to open all the rad valves and turn the pump on full. There is a switch on the pump in most cases with three settings. This may blow the air or blockage through

/quote]
Can also help if you turn all the other rads OFF to direct all the flow towards (and hopefully through) the dodgy rad.

Have to say I am sceptical about an underfloor pipe being blocked. It can happen, of course, but it is much more likely to be the TRV pin being stuck (very very common), or the rad needing bleeding (but would usually still be warm at the bottom), or just possibly the lock-shield valve having been closed for some reason (eg if it had been removed for decorating during the summer).

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Re: Blocked heating pipe

#4112

Postby IsleofWightPete » November 12th, 2016, 11:31 am

Snorvey wrote:
My mother did say that the engineer said that it might take a day or 2 for it to start working properly again, so I dunno if that gives any pointers?


The only thing that I can think of that might be slow acting, is if he put some system cleaner in.
eg something like: https://www.sentinelprotects.com/uk/pro ... te-cleaner
However, that should really be flushed out again after a few days, system drained down to get rid of the loosened sludge, flushed through with clean water, and then system filled (and inhibitor added).
So, maybe he is planning a revisit to complete that job?

I can't think of anything else that might have delayed results.

I suppose he might have just increased pump speed and wondered if that would work it free over time, but that would be a bit hit and miss.

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Re: Blocked heating pipe

#4135

Postby CatcheeMonkee » November 12th, 2016, 12:19 pm

Snorvey wrote:
My mother did say that the engineer said that it might take a day or 2 for it to start working properly again, so I dunno if that gives any pointers?


Enough time for the cheque to clear ... ??? :)

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Re: Blocked heating pipe

#4156

Postby 88V8 » November 12th, 2016, 1:14 pm

Pipes should never block.
If there's sludge in there, it's because there is insufficient water treatment chemical in the system.
This is important.
Without sufficient chemical, the system will not only sludge, but the pump will be buggered and the radiators will rust through.
You can check in the header tank, using one of these:
https://www.sentinelprotects.com/uk/pro ... k-test-kit

One symptom is that when you bleed the rads, there is a smell of rotten eggs. Indeed, in a well installed and maintained system the rads will never need bleeding, ever.
If as I expect there is insufficient treatment, or none, then go to the local plumber's merchants and buy some, drain off some of the water and refill.
It's not cheap, and as most houseowners know nothing about how central heating works, so-called heating engineers often skimp on water treatment knowing it will be a while before the problems emerge.

You'll need to calculate how much water is in the system, so you know how much treatment to put in.
http://www.fernox.com/problem+solving/h ... tem+volume

V8

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Re: Blocked heating pipe

#8422

Postby Mike4 » November 24th, 2016, 5:17 am

IsleofWightPete wrote:Can also help if you turn all the other rads OFF to direct all the flow towards (and hopefully through) the dodgy rad.

Have to say I am sceptical about an underfloor pipe being blocked. It can happen, of course, but it is much more likely to be the TRV pin being stuck (very very common), or the rad needing bleeding (but would usually still be warm at the bottom), or just possibly the lock-shield valve having been closed for some reason (eg if it had been removed for decorating during the summer).


Pretty much exactly what I would have said too, had IoWP not arrived and said it two weeks ahead of me!

:D

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Re: Blocked heating pipe

#10025

Postby alterego » November 29th, 2016, 1:59 pm

A bit of a post script on this but all sorts of things are possible when the heating isn't working properly as illustrated by my experience. For some years after I bought a new house, one radiator was always cool despite bleeding etc. I was also aware of a tinkling sound whenever the pump was running. Later, when I was installing new radiators in a different location, I had to take up the floorboards and cut the copper piping. As I lifted out a redundant section of pipe the cause of the tinkling and the cool rad became apparent.

Out rolled a perfectly spherical ball of cement which must have been there since installation. Builders, don't you just love 'em?

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Re: Blocked heating pipe

#18972

Postby IsleofWightPete » December 31st, 2016, 12:24 pm

Snorvey wrote:
If you have an existing traditional central heating system and a hot-water cylinder, there is usually nothing to be gained from replacing the boiler with a combi.


I would agree with that. If you don't need the space (from removing HW tank) I would stay with a system boiler.

I'm assuming the system is being topped up from the F&E tank? I pushed it up to 1 bar via the fill loop, but I expect by tomorrow it will be zero again.

Snorvey


If you are topping up from a fill loop, I would assume that the F&E tank is not connected.
It should be either / or, not both.
The fill loop will pressurise the system, and if you are saying the pressure goes up when you fill via the fill loop, I would suggest that is definitely connected.
Often things like header tanks are left in situ rather than removed. Not best practice, but often done on the basis "it's not hurting anyone where it is"

The question of where the pressure is going is another matter!
First port of call is to check the pressure relief pipe to see if water is dripping out.
It is very common for a bit of crud to lodge in the pressure relief valve and stop it sealing properly, allowing a steady weep.
This can often be cleared by flicking open the valve a few times (which can clear the crud) or a replacement is not xpensive.
Check that is the problem by taping a small poly bag on the end of the pipe. (Note this is not the same as the condensate pipe, which should be discharging into a drain. The PR pipe should go outside close to the boiler, and generally should be tuned back to point at the wall - often only a few inches of pipe)

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Re: Blocked heating pipe

#18975

Postby IsleofWightPete » December 31st, 2016, 12:30 pm

Having further checked, I see in the manual that "Mini boilers are suitable for fully pumped pressurised
sealed systems only"..........
http://idealboilers.com/wp-content/uplo ... i_is32.pdf
(Page 10)
..... which is why they F&E tank will have been disconnected.

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Re: Blocked heating pipe

#19057

Postby quelquod » December 31st, 2016, 4:53 pm

Snorvey wrote:So it running at no water pressure will mean......? (I'm hoping it wont blow up or anything!) Will it just run out of water and shut down?

Boilers generally shut down gracefully when the pressure falls below a given level, typically around 0.5 bar or so. In the meantime just keep filling it up to (say) about 1 - 1.5 bar (cold), no more, as and when (as long as you're sure the escaping water isn't doing any harm of course).

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Re: Blocked heating pipe

#19075

Postby IsleofWightPete » December 31st, 2016, 5:40 pm

As already stated, the boiler will shut off if pressure gets too low.

But don't assume this is a boiler problem.
Pressure loss CAN be down to a fault in the boiler, but it can also be a fault in the plumbing elsewhere in the system (leaking joints, seeping valves, etc). In my personal experience, it has nearly always been the latter - but I don't know how typical my experience is for the rest of the market!
So don't let someone talk you in to replacing the boiler unless they have demonstrably located the leak. Otherwise you can find you have a nice expensive new boiler and still have the same problem with falling pressure.

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Re: Blocked heating pipe

#19096

Postby quelquod » December 31st, 2016, 7:13 pm

Just to add to what Pete has said, don't assume that you need to have a huge leak somewhere which would be easily noticed. As little as a single drip of water a minute would lose all the pressure in an average system in under a week and depending on where it was could pass undetected in a warm house.

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Re: Blocked heating pipe

#19941

Postby IsleofWightPete » January 4th, 2017, 12:46 pm

Snorvey wrote:Quite unusual last night as the pressure had gone up to 2.4 bar (I had set it to around 1.5 bar a couple of days prior to that). Today though, it's dropped to 0.5 bar (but still running). Something weird going on here.


Aaaaaah!
That sounds like your expansion vessel is knackered (or just needs recharging).
When the water heats up, it expands. Because the system is sealed, the extra volume needs to go somewhere.
So there is an expansion vessel, something like this
https://www.dhsspares.co.uk/product/ide ... 8l-1179334
(I don't think that's the right model for your boiler, just an example)
In between the two domed halves is a rubber diaphragm. On one side is pressurised air (which can compress further to absorb the expansion of the water) and the other side is full of water connected to your heating circuit.

If the air leaks out, then the diaphragm will move completely to one side, filling the whole space with C Heating water. Then, when the water expands, it has no where to go. Pressure build and builds, until some water discharges out of the pressure relief valve, because it can't compress like air can.

When the system cools down again, there is too little water left in the system (because some has been discharged outside) so the pressure is low.

That sounds a lot like your symptoms. High pressure when hot, low pressure when cold.

Sometimes the vessel can be recharged - it has a car tyre type valve on it and you can literally pump it up with a car tyre pump.
But often the diaphragm has become perished or perforated, so recharging is only a temporary solution, but replacement is not expensive, depending on the design of the boiler. Sometimes the boiler needs taking off the wall to change the damn thing. Others are more accessible and it is a quick and simple job.

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Re: Blocked heating pipe

#20069

Postby staffordian » January 4th, 2017, 7:36 pm

Snorvey,

Its often simpler to add an external expansion vessel rather than buy the branded one which fits inside the boiler.

I have an Ideal Isar which exhibited the same symptons as your boiler, and the expansion vessel was not only expensive, it was quite inaccessible, and would have involved an engineer dismantling a fair bit of the boiler to get to it.

Having done a bit of research, I asked my plumber if he could fit an external vessel and he agreed it would sort the problem.

It was a fraction of the cost*, and with the added bonus of being more accessible in future if repressurisation was needed.

Staffordian

*Examples here http://www.screwfix.com/c/heating-plumb ... ionvessels

IIRC an Ideal vessel was approaching three figures

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Re: Blocked heating pipe

#20256

Postby staffordian » January 5th, 2017, 10:39 am

Snorvey wrote:I went down this morning to check the boiler. Pressure down and I didn't even need the binoculars to check the outside copper pipe (which looks exactly as you described). There is a stream of water down the wall and on to the pavement below coming for the outlet.


If I were a betting man I would wager a very large amount that it is the expansion vessel. Not necessarily faulty, quite possibly it simply needs repressurising as IOWP mentioned above.

Staffordian


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