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Andrew Smith
Andrew Smith, Home Appliance Technician
Category: Appliance
Satisfied Customers: 3629
Experience:  Gas cooker specialist
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The needle is going from zero to well into the red section

Resolved Question:

The needle is going from zero to well into the red section (with flashing number of over 3) depending on whether I have the tap underneath at 12 o'lock or 3 o'clock. I don't want it to blow up or to be cold. Help!
Submitted: 2 years ago.
Category: Appliance
Expert:  Andrew Smith replied 2 years ago.
***** ***** : Turn it back to 3 o'clock to shut the water off again and tell me what it does
Customer:

I am having to go up and down stairs.

Customer:

It is on 2.6 and no lights are on (after turning off water).

Customer:

Shall I wait for reply? or was that it?

Customer:

Now what? Is that it? Am I supposed to rate the answer, and call it a day?

***** ***** : Are you losing water out of the 15mm discharge pipe
***** ***** : How fast does the pressure drop?
Customer:

I have no idea what that is?

Customer:

I shall have to go down again to look at the boiler.

***** ***** : Do you have water running down the outside wall under the boiler?
***** ***** : Plenty of time
***** ***** : Let's just do this one step at a time and get it right
Customer:

Ah! I will have to go outside.

Customer:

It is now 2.2 with yellow light on.

***** ***** : If the PRV cannot hold pressure then you will have to replace it before the boiler will work fully
Customer:

It appears to be dry outside. Now 2.3.

***** ***** : If it is not leaking from there then it will either be internal to the boiler in the heat exchanger
***** ***** : Or on your central heating system
Customer:

What shall I do until next week when people start work again? Leave hot water switched off?

***** ***** : Lets see if it holds pressure first
Customer:

It is still 2.3.... seems to be holding pressure. Shall I just leave the hot water off so that I can have heat?

***** ***** : Do you only get problems when the hot water is on?
***** ***** : Does the pressure rise rapidly when the heating is on?
Customer:

Well, I haven't switched off the hot water until you told me to.

Customer:

I am not sure what counts as rapid. It doesn't take a long time to rise or fall, (depending on whether I'm trying to raise or lower it).

***** ***** : No when the filling point is off
***** ***** : and the boiler is running normally
***** ***** : I am wondering why it was so low to start with?
Customer:

Sorry, you have lost me. I'm a 65 woman without much skill in the machine dept.

***** ***** : When you turned the filling point off to the boiler, did you also turn off the hot water?
***** ***** : I do not understand?
Customer:

I wondered why the heating hadn't come on in the morning and found it was on zero. I then mucked about with the tap. (And now I can't remember whether it is normally at 12 or 3).

***** ***** : ok, when the valve is at right angles to the pipe then it is off
***** ***** : Perhaps everything is fine now?
***** ***** : The boiler is full, you should try the heating and hot water....
Customer:

. When I turn the tap is that what I'm doing? Turning the filling point on and off?. OK. I will turn on the water again and see what happens.

***** ***** : Yes - have you turned off the water to the house also?
Customer:

1) I didn't touch the water to the house, just switched off the hot water on the boiler. (2) The tap is at right angles to the pipe; the hot water is on; the number is ***** and didn't change over a minute.

***** ***** : Ok, good.
***** ***** : When you said turned off I thought you meant with a tap
***** ***** : Let the boiler work as normal and keep an eye on the pressure
Customer:

And if it rises or falls?

***** ***** : It is slightly high at 2.4, but you can always bleed a radiator into a bowl to bring it back down to 1.5 bar
***** ***** : It should rise slightly when heated and the water expands, but no more than 1/2 bar
Customer:

That takes me to places I've never been....bleeding a radiator into a bowl seems challenging. I'm not sure I have a bleeder key. Please tell me again.....should the tap be at right angles to the pipe or parallel? If the pressure is low (or high) which way do I turn the tap. Sorry I'm not much good at this.

***** ***** : Leave the tap closed (at right angles to the pipe)
***** ***** : The pressure should not rise apart from slightly when heated
***** ***** : If the pressure drops then top it up again by turning the valve back on and then off again at 1.5 bar
Customer:

And to bring the pressure down.... can I do anything with the boiler or does it have to be bleeding a radiator?

***** ***** : Bleeding a radiator is the easiest way, but get someone else to do it for you tomorrow if needed
Customer:

Oh dear. I turned the tap and it shot up to 2.8. I've switched off hot water and heating, and will hope it goes down. When it gets to 1.5 I shall switch on heating again. I need someone who knows what they are doing.

Customer:

Right. What seems to be happening is that when the heating is off, the pressure gradually drops. My guess is that it eventually hits zero. What does this mean and what do I do?

***** ***** : This means you have a leak
***** ***** : If you are not losing it through the copper pipe outside then it will be on the heating system somewhere.
***** ***** : You do not need to turn the tap on again until it drops below 0.5 bar
***** ***** : Leave it off and turn your heating and hot water back on.
***** ***** : Your boiler has so many safeties built in that it cannot do any damage
Customer:

1) Right. I was waiting until it reached 1.5 before turning heating on again. (2) So I need a plumber or heating engineer. Can I last out until Monday when people are back at work? (3) should I go round the house looking for a leak by each rad? and look outside again in daylight (4) no damage even it goes up to 3.5?

***** ***** : Your PRV will discharge at 3 bar - so no damage can be done by overpressurisation
***** ***** : Wait until the pressure has dropped and then turn the hot water and heating back on on the controller or fascia
***** ***** : If the pressure drops too low then top it back up again slowly
***** ***** : Repeat until you can get a heating engineer out next week when it is cheaper
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