# Pipes are frozen, tank is empty, can I use the heating?



## Petit (5 Jan 2010)

Hi there,
We are 4 days without water. We reckon the pipes are frozen. The mains went first and then we drained the tank. We now realise this was foolish. Can we still use the oil fired heating?? It's off at the moment but this weather is not improving and I'm getting mixed advice. Thanks in advance.


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## onq (5 Jan 2010)

Petit,

You need to take competent advice.
You must have a plumber locally you can ring.
I would be very wary of running it if there's no water left in the Hot Water Cylinder.

Equally you need to heat your house.
We keep a couple of small electric blower type heaters for emergencies.
The day we moved in was a Friday in February and the Bórd Gáis guy disappeared five minutes before we arrived.
We had an eight month old baby and a freezing house so I nipped around to DID electrical and bought a heater to do us over the weekend.

Also we lit the fire in the front room - no back boiler to worry about - if you have one be wary of lighting the fire.

HTH.

ONQ.


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## Petit (5 Jan 2010)

Thanks ONQ,

Yes, I have a couple of portable oil heaters on the go and a fire lit all the time (no back boiler!) but like you I have a small child and it would help to put the heat on but I am wary. I'm going to ring the plumber tomorrow. 

I wish I had know this in advance I would have kept the tap on a trickle. I'm here 8 years and never had this happen! Thanks for the reply. Petit


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## DavyJones (5 Jan 2010)

Use the heating, the hot water cylinder isn't empty, even if it was it has no bearing on your heating.


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## Bronte (6 Jan 2010)

I had pipes that bust many years ago, the plumber installed a light or heat to the pipe near the tank in the attic so it would never happen again.  I'd recommend it to anyone having frozen pipe problems.


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## onq (6 Jan 2010)

DavyJones said:


> Use the heating, the hot water cylinder isn't empty, even if it was it has no bearing on your heating.



How do you know the HWC has water in it?

ONQ.


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## delgirl (6 Jan 2010)

My neighbour had the same problem, but was able to use his oil-fired central heating without a problem.

He also cleverly connected a long hose to a neighbour's outside tap and was able to fill the tanks in the attic.


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## SparkRite (6 Jan 2010)

onq said:


> How do you know the HWC has water in it?
> 
> ONQ.


 
Think about it ONQ, and then tell me how it could possibly empty?

Clue: What drives the water through the HWC ?


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## Leo (6 Jan 2010)

SparkRite said:


> Think about it ONQ, and then tell me how it could possibly empty?
> 
> Clue: What drives the water through the HWC ?


 
Aw, I really want to answer that one but feel I might be spoiling ONQ's test


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## Towger (6 Jan 2010)

onq said:


> How do you know the HWC has water in it?.



What, I thought you were an expert on all building matter!


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## W200 (6 Jan 2010)

Have a look in the attic and see if there is another small water tank ( Header tank ) positioned above the main tank . So long as there is water in this tank then heating is safe to use . If you do not have a header tank then you must have a "Closed" heating system which has a pressure gauge on the system to show if there is water there. If you know where this gauge is and pressure is normal then system is safe .


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## onq (6 Jan 2010)

<chuckle>

Oh dear, here we go...

"Competent to comment on all matters in relation to buildings" is what I claim.

I'm very wary of claiming expertise above and beyond that of a competent practitioner in my profession.
[I also worked as a plumbers mate at one time but I tend to stick to what I'm good at these days].

Hot water cylinders may have two means of heating the domestic water supply; -
i) an electric element, the so called immersion heater
ii) a coil fed by the boiler - the indirect heating method

The water in the coil doesn't mix with the water in the cylinder.
The water in the cylinder is for domestic use - HW taps, showers etc.

A separate boiler pipe feeds the radiators - the Primary circuit - and the boiler/rad systems is kept topped up by, and expands into, an expansion tank.
This is smaller than and often separate from the main tank.
You can sometimes see the smaller tank perched above the larger one on older indirect systems.

The hot water cylinder cylinder therefore regularly empties, refilled by water from the main attic tank, with hot water being drawn off to the HW taps throughout the house.
The HWC will eventually empty if the main tank is drained and the main tank supply cut off and people continue to use the hot taps in the house.

The Primary circuit passes into and out of the HW cylinder at top and bottom.
Like the immersion, it is designed to heat a cylinder full of water, not full of air.
I have seen HWCs fail at these connection points.
Thus my concern that I would be wary of running a heating system for any length of time when the HWC is empty.

I am happy to stand corrected or receive some wisdom on the matter.



ONQ.

PS I'm assuming this is the method of heating used.
It may be an older house with a totally separate heating system in which case no problems may arise
It may be also possible to shut of the branch to the presumably empty HWC.


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## onq (6 Jan 2010)

W200 said:


> Have a look in the attic and see if there is another small water tank ( Header tank ) positioned above the main tank . So long as there is water in this tank then heating is safe to use . If you do not have a header tank then you must have a "Closed" heating system which has a pressure gauge on the system to show if there is water there. If you know where this gauge is and pressure is normal then system is safe .



The OP speculated that the cause of the water supply failure was frozen pipes.

Some residual heat may have kept the water in the header tank liquid, but the uninsulated overflow pipe in the attic might have frozen.

Unless of course we have a plumber reading here who could state that these kinds of things never happen.

ONQ.


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## Petit (6 Jan 2010)

Hi there, thanks for all the replies!! We reckon it is the outside pipes under pavement and field that are frozen. We don't have another house within a mile of us to feed water into our tank, sadly! The house is only 8 years old and as I say it is the first time it has happened but it is bitter here. 

Everything is frozen solid outside. Waiting for return call from plumber!! I think he's busy!


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## Leo (6 Jan 2010)

onq said:


> The HWC will eventually empty if the main tank is drained and the main tank supply cut off and people continue to use the hot taps in the house.
> 
> I am happy to stand corrected or receive some wisdom on the matter.


 
Good to hear that last bit 

The HWC fills from the bottom, drains from the top. When you open a hot tap, the pressure from the cold feed atthe bottom forces hot water out the top of the tank. Ideal really as the water at the top is the hottest within the tank. Where dual coil immersion elements are used, the shorter 'sink' coil only heats the top portion of the tank.  
Leo


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## villa 1 (6 Jan 2010)

If mains water service pipes are buried at the proper depths they will not freeze (760mm) The trouble starts when they are not deep enough and sharp sustained frosts freeze them up. Pouring boiling water over external stopcocks on pipes that are not buried deep enough will only add to the problem. Bob the builders had a habit of installing service pipes at shallow depths leading to freezing problems.
Wait till the thaw and we'll have loads of leaks. Frozen pipes don't leak, the ice breaks pipes and connecting fittings. It's when they start defrosting the trouble occurs!!


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## SparkRite (6 Jan 2010)

onq said:


> <chuckle>
> 
> 
> The hot water cylinder cylinder therefore regularly empties, refilled by water from the main attic tank, with hot water being drawn off to the HW taps throughout the house.
> The HWC will eventually empty if the main tank is drained and the main tank supply cut off and people continue to use the hot taps in the house.


 
ONQ you're not stopping to think about this......

As water is drawn from the HWC it is (normally) forced out by the driving water from the header tank. 
The amount drawn off equals the amount "gravity fed" in. Therefore, remove the "driving force" (by whatever means) and no water will flow through the HWC ie. it remains full, no matter how many taps are open.


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## Dirac (6 Jan 2010)

We had the same problem on Christmas day. Tanks were drained in attic. Turned out that pipe from well pressure vessel had frozen. Turned well pump off, closed outlet valve, undid well pipe and used the steam cleaner to shoot steam down the water pipe (mind your hands!) and then connected it all up again. Thought I had the problem fixed when I checked the header tanks in the loft had filled up but still no water running apart from kitchen and utility cold which comes straight from the inlet rather than tanks (apparently cos of better pressure for washing machine and dishwasher). Eventually located the problem. Ours is a pumped system and the pump which pumps cold water had safety cut out when no water was coming from headers. pressed the reset button and hey presto, air and water venting from taps and all sorted! Hope this helps


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## onq (6 Jan 2010)

Leo said:


> Good to hear that last bit
> 
> The HWC fills from the bottom, drains from the top. When you open a hot tap, the pressure from the cold feed atthe bottom forces hot water out the top of the tank. Ideal really as the water at the top is the hottest within the tank. Where dual coil immersion elements are used, the shorter 'sink' coil only heats the top portion of the tank.
> Leo



So the colder denser water stays at the bottom and the hotter water stays at the top and is drawn off.

Thus the level cannot fall below the outlet of the tank unless there is a leak ower down.

I presume there is some sort of valve at the base ot drain it off it work is necessary on the tank.

Nice to learn something again.

I say again because I'm sure I discussed this with someone before [a plumber no doubt] and knew it, but forgot it.

Thanks Leo.

ONQ.


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## Petit (6 Jan 2010)

Villa 1, I think you hit the nail on the head, Bob the builder did not put them down far enough hence our problem. Still not heard from plumber!


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## W200 (6 Jan 2010)

Leo said:


> Good to hear that last bit
> 
> The HWC fills from the bottom, drains from the top. When you open a hot tap, the pressure from the cold feed atthe bottom forces hot water out the top of the tank. Ideal really as the water at the top is the hottest within the tank. Where dual coil immersion elements are used, the shorter 'sink' coil only heats the top portion of the tank.
> Leo


 
Hi.
Just to keep the discussion going , would it be correct to say that with prolonged use of the heating AND an empty attic tank the water in the cylinder would eventually evaporate resulting in damage to the cylinder ?
w200


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## onq (6 Jan 2010)

SparkRite said:


> ONQ you're not stopping to think about this......
> 
> As water is drawn from the HWC it is (normally) forced out by the driving water from the header tank.
> The amount drawn off equals the amount "gravity fed" in. Therefore, remove the "driving force" (by whatever means) and no water will flow through the HWC ie. it remains full, no matter how many taps are open.



Sparkrite, you're correct.

I wasn't thinking it through, but Leo and you have clarifed the position.

Once the level of the water in the supply pipe from the attic reaches the level of the outlet in the tank no more can flow out.

Thanks.

ONQ.


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## Petit (6 Jan 2010)

Dirac, thanks for that. We are actually on the mains supply not a pump system so not sure if any of that applies to me. I can't even get in attic to see tank etc as I need a set of ladders and hubby is away!! I'm afraid I'll get in more trouble if I try to go up there!


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## DavyJones (6 Jan 2010)

W200 said:


> Hi.
> Just to keep the discussion going , would it be correct to say that with prolonged use of the heating AND an empty attic tank the water in the cylinder would eventually evaporate resulting in damage to the cylinder ?
> w200




No damage would be done to cylinder. the only problem that may occur is if a house has leaks that have went unnoticed as the header tank (small tank) in attic normally refilled itself. After a prolonged absence of water, the heating system may become empty, even then stat at boiler would shut it done before any real damage could occur, real damage being a burnt out pump.

Oh and Sorry ONQ for the short answer last night, I finished work at 11pm, If I never see another frozen/burst pipe it will be too soon.


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## Petit (6 Jan 2010)

DavyJones said:


> No damage would be done to cylinder. the only problem that may occur is if a house has leaks that have went unnoticed as the header tank (small tank) in attic normally refilled itself. After a prolonged absence of water, the heating system may become empty, even then stat at boiler would shut it done before any real damage could occur, real damage being a burnt out pump.
> 
> Oh and Sorry ONQ for the short answer last night, I finished work at 11pm, If I never see another frozen/burst pipe it will be too soon.


 
Thanks DavyJones for confirming that and for all the replies. Just had the plumber on and he said as long as the pipes on the boiler aren't frozen it should be fine and he installed it so yipee, I'm off to turn on the heat!! 

All I need now is water!


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## SparkRite (6 Jan 2010)

onq said:


> Nice to learn something again.
> 
> I say again because I'm sure I discussed this with someone before [a plumber no doubt] and knew it, but forgot it.
> 
> ...


 

No problem ONQ.
Everyday is a schoolday.


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## Leo (7 Jan 2010)

onq said:


> I presume there is some sort of valve at the base ot drain it off it work is necessary on the tank.


 
No prob ONQ, like to feel like I know something every now and then 

Yes, there will be a drain-off point at the bottom of the tank.
Leo


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## Callisto99 (9 Jan 2010)

Hi,

I believe I am in a similar situation - Stopcock from the mains is no more than a ft down and no water from the mains at entry point under the kitchen sink. 

Distance of approx 7metres from stopcock to the entry point to the house - is there any way to thaw out this pipe?

Heating has been working but is there a risk of doing damage from this? OFCH by the way.

Thanks in advance,
C


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## Vapona (10 Jan 2010)

W200 said:


> Hi.
> Just to keep the discussion going , would it be correct to say that with prolonged use of the heating AND an empty attic tank the water in the cylinder would eventually evaporate resulting in damage to the cylinder ?
> w200



Not at all. I have just this scenario running here and has been for the past several months. The hot cylinder (a temporary installation, not needed for the main residence) sprung a leak and I drained it. The CH has been running the cylinder coil in an empty tank for ages with no detriment. What you mustn't do is accidentally switch on the immersion heater, of course.


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## DGOBS (10 Jan 2010)

Hi Guys, just one thing to add, once your heating is running, it can be helpful to partially open the attic door to allow some warm air to circulate and prevent the pipes up there from freezing as no water will be flowing
(I know mine has been open since I lost water!)


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## Henley (16 Jan 2022)

Petit said:


> Villa 1, I think you hit the nail on the head, Bob the builder did not put them down far enough hence our problem. Still not heard from plumber!


Did you ever find out if you could use the oil heating in the end?


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## roker (18 Jan 2022)

onq said:


> How do you know the HWC has water in it?
> 
> ONQ.


The primary system for the rads and hot water does not empty unless specifically drained, it is a different header tank to the hot water tank or a sealed recirculating system


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## noproblem (18 Jan 2022)

Henley said:


> Did you ever find out if you could use the oil heating in the end?


After 11 years i'd say she's flowing soundly


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## ClubMan (18 Jan 2022)

Cynic that I am, I wondered how many of the original contributors to this thread are now deceased...


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## AlbacoreA (18 Jan 2022)

roker said:


> The primary system for the rads and hot water does not empty unless specifically drained, it is a different header tank to the hot water tank or a sealed recirculating system



... or there's a leak in it.


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## W200 (26 Jan 2022)

ClubMan said:


> Cynic that I am, I wondered how many of the original contributors to this thread are now deceased...


Still going ........ Just


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