How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • Go back-and-forth until satisfied
    Rate the answer you receive.
Ask Tim JA Your Own Question
Tim JA
Tim JA, Engineer
Category: Plumbing
Satisfied Customers: 2341
Experience:  Owner at Self-employed
Type Your Plumbing Question Here...
Tim JA is online now

I have a broblem with my gas boiler. It's working but

This answer was rated:

Hi. I have a broblem with my gas boiler. It's working but everytime I turn the heating on the water pressure is jumping and the boiler makes choking sound. What could be a cause of that.? Radiators are bled
JA: Are you getting any error codes or blinking lights on your boiler? How old is it?
Customer: It's probably 12 years old. No it's an old type gas boiler with no screen on it
JA: How long has this been going on with your boiler? What have you tried so far?
Customer: I've bled the radiators. It's like that for 2 months but the sound it's getting worse
JA: Anything else we should know to help you best?
Customer: Nope

Good afternoon, welcome to the Technical section in JustAnswer; my name is ***** ***** I will help you today.

Your problem initially sounds like poor (or no) circulation. What is the make and complete model number of the boiler?

If you receive a phone call offer, please ignore it - these are system generated and outside my control. My understanding is that you won't be charged if there's no phone call.

Customer: replied 1 year ago.
It's Vokera Mynute 16e

OK. This is a system boiler, so any boiler fault would affect both hot water and central heating equally. Do you get any of the banging symptoms when heating the hot water?

If not, please tell me what MZVs (motorised zone valves) you have in the system. These can have silver metal box attached to a black cable, or a white plastic box, or sometimes a blue plastic box.

Customer: replied 1 year ago.
I do get a banging-chocking sound in the gas boiler.
Customer: replied 1 year ago.
pressure is jumps from 1.5bar to 2.5bar while heating is on
Customer: replied 1 year ago.
Pressure jumps*

Please could you read my questions again?

Customer: replied 1 year ago.
I have a banging symptoms when heating the hot water.

OK. My hunch is that the system pressure is too low. Could you tell me the reading on the pressure gauge when the boiler is cold?

Customer: replied 1 year ago.
It is cold right now and the pressure is 1.3 bar
Customer: replied 1 year ago.
File attached (7ZLMM4L)

OK. This boiler doesn't have a differential water pressure sensor, so the next most likely possibility is a failed circulating pump.

Have you had any occasions recently where the radiators don't get very warm, or the hot water takes a long time to heat up?

Customer: replied 1 year ago.
It takes longer to heat up the water.

And were the upstairs radiators tending to get hotter than the downstairs ones, or were they performing the same?

Customer: replied 1 year ago.
Upstairs is really hot. Downstairs not so much

My money is on a failed/failing pump. Is the diagnosis and fix something you're thinking of going yourself?

Customer: replied 1 year ago.
If its a failing pump I think I'm gonna call a plumber to come and fix it

You will need a Gas Safe registered engineer, not a plumber, because the pump is inside the boiler casing. Do you have the details of the engineer who last serviced the boiler?

Customer: replied 1 year ago.
I do. I will ring him Monday morning.

Sorry that there's no quick fix for this. I hope that your engineer can come soon.

Customer: replied 1 year ago.
It's ok. Just wanted to ask you quick question. Is it expensive to repair that?
Customer: replied 1 year ago.
thanks for your answers. Really appreciate that

You're welcome :-)

Tim JA and other Plumbing Specialists are ready to help you

Thank you for your rating, and the kind bonus :-)

I just saw that I missed your question, sorry...

The engineer will need to arrive at their own diagnosis of the problem and then give you a price for fixing it. Even though I think it's the pump I can't tell you the cost of the part without looking it up, and the job might involve other materials, for example corrosion inhibitor, so it's impossible to give a price without visiting.