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Tim JA
Tim JA, HVAC Technician
Category: HVAC
Satisfied Customers: 3266
Experience:  Owner at Self-employed
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We've had suspected thermostat stop working with an electric

Customer Question

Hi there! We've had suspected thermostat stop working with an electric immersion heater, so the heater's been completely switched off and it's just cold water running through the heater. Our plumber's coming next week. However, the water is now flowing out of the building through the overflow pipe and I was wondering how to cut the water supply off to the heater? I know it's one of the valves, but not confident which one
JA: When did you last replace or repair the pipes? Is the air around the pipes humid or dry?
Customer: We're renting from a landlord so unsure of the former, air seems to be dry round pipes and it's a completely electric house so no gas system
JA: What have you tried so far with your pipe?
Customer: Nothing other than cutting off the electricity
JA: Anything else we should know to help you best?
Customer: This has been an issue since Wednesday, there haven't been other issues other than the one at hand
Submitted: 16 days ago.
Category: HVAC
Customer: replied 16 days ago.
Here's a photo of the valves by the immersion heater
Expert:  Tim JA replied 16 days ago.

Good afternoon, and welcome to the Technical section in Just Answer, an independent paid question and answer platform that matches customers' questions to experts in various skills. My name is ***** ***** I'll be happy to help you today.

I'm sorry to hear of your hot water problem.

I can't tell from a photo of a valve what that valve is connected to, so you would need to attach a photo showing everything that's in the cupboard for me to be sure of working it out.

However, where is the water emerging from?  I suspect it's not related to the problem with the thermostat.

Customer: replied 16 days ago.
Thank you, ***** ***** water is running through the heater and out the what i assume is the overflow pipe out the side of the building. I've attached images of both the full cupboard and the overflow pipe outside
Expert:  Tim JA replied 16 days ago.

Ah, you have a combination cylinder. This is a cylinder with a header tank sitting on top.  If that reservoir level is too high, water will come out of that warning pipe.

The valve that you need to shut is the brass stop cock that's a few inches below the timer.  The valve is in the lower part of your first photo.

Customer: replied 16 days ago.
Thank you! Thought as much, unfortunately I've just tried to turn it and it's completely stiff, may need some WD40
Expert:  Tim JA replied 16 days ago.

I recommend that you do not use WD40, as (a) it's unlikely to reach the part that's stuck, and (b) if it did then it will pollute your water supply.

Expert:  Tim JA replied 16 days ago.

The best way to get it moving is with a ring spanner or a large adjustable wrench.  If is frees off then that's fine, but it remains very stiff then be careful as that's when the spindle shears.  When they are very stiff and/or the handle breaks off then you'll have to replace the stop cock.  As it's not your property then of course you're taking on a liability that you might not want to.

Customer: replied 16 days ago.
Quickly gave it a go, the pipe was more flexible than the tap so I've just retreated for now. You're absolutely right on the liability front, a bit awkward when the property's not yours but the water bills are! Looks like I may have to just wait for the professional to show up on Tuesday and try and claim it back later. I'd have got someone in the day after it happened, but the landlords have been firm that we must wait for their plumbers to deal with it - at least you've helped in making sure I'm not completely in the dark here, so thank you
Expert:  Tim JA replied 16 days ago.

You're welcome.  And I do sympathise with the water wastage and the cost of it.

Just a thought - if you measure the flow rate then you could ask your landlord to pay for the excess water used.  If you take an ordinary kitchen measuring jug, you can use the stopwatch app on a phone to time how long it takes to fill it.  Here's a worked example:

45 seconds to fill a jug to the 500ml mark.
Litres per hour =( 60*60) / 45*2  = 28.9 litres per hour.
That would be 694 litres day. 
From that you can work out the cost of the water being wasted, but 694 litres is about 144 days of normal usage for the average household, so it could be a lot.