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Tim JA
Tim JA, Construction Worker
Category: Home Improvement
Satisfied Customers: 2341
Experience:  Owner at Self-employed
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I had google termostat gen 3, it worked few days properly

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I had google termostat gen 3 , it worked few days properly than we don't get hot water it shows schedule on but still no hot water
JA: What's the brand and model of your thermostat?
Customer: radiotors working
JA: How long has this been going on with your thermostat? What have you tried so far?
Customer: re-startted
JA: Anything else we should know to help you best?
Customer: heating is working but no hot water it comes when we run the tap after 2 minutes cold again

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

Do you have stored hot water, or a combi 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.
File attached (MTM347P)
Customer: replied 1 year ago.
I attached the picture of it , I believe it s stored hot water

Yes you have stored hot water. So, for some reason the boiler isn't heating the tank of water.

Have you configured a schedule on the Nest to heat the hot water?

Customer: replied 1 year ago.
I want non stop hot water and schedule on 24/7 still not working.
Customer: replied 1 year ago.
Yeah , its on non stop because we want hot water non stop.

OK. So the fault is likely to be either the motorised valve or the cylinder thermostat, or the system wiring.

Can you tell me the make and model of those components?

Customer: replied 1 year ago.
I have attached the model of cylinder termostat

OK thank you.

Below the boiler there is a silver box with a black flex to it. Is there a similar box near the cylinder?

Customer: replied 1 year ago.
Could not find it

OK. I suspect the second motorised valve is closed to the first one, perhaps directly under the boiler. I can't see that area clearly as there is a discarded insulation bag in the way. Could you check around there?

BTW, I'm acutely concerned about the open electrical junction box near the cylinder, so please be careful with that until you can get a cover on it.

Customer: replied 1 year ago.
Do you think valves need to change?

There are several ways in which they can misbehave and/or fail, but we haven't yet reached the point of knowing whether or not there's anything wrong with them.

There is a test to discover the behaviour of the valves, which is what I'm heading towards, but there are different brands and models, so the steps in the test depend on which you have.

Please bear in mind that fault-finding is a process, especially when doing it remotely. It necessitates questions and answers in both directions, and very rarely is there an obvious cause from the very beginning.

Customer: replied 1 year ago.
Yeah second one under the bag

OK. So that second MZV (motorised zone valve) is a Honeywell valve, and it looks like the pipe from the right hand end of it is running to the hot water cylinder. I'll proceed on that basis unless you tell me I'm wrong.

The purpose of the MZV is to open the flow to heat the cylinder, and then to provide the signal (a heat demand) to the boiler to ignite. If the MZV malfunctions, then the boiler won't have a heat demand.

The MZV responds to a signal (a "call") from the cylinder thermostat. Those can malfunction too. This chain of signals originates at the programmer. So, a quick and easy observation is to see how the MZV valve behaves, and work back from there.

On the end of the silver box, under the black cable, there's a thin metal lever in a slot. Please can you attempt to push the lever along the slot, and let me know if it feels floppy, or do you feel resistance? If you feel resistance, push the lever to the end of the slot and release it - does it spring back?

Customer: replied 1 year ago.
It stays on auto is that right?

One moment - I need my phone to watch the video...

No that's not right. You need to push the lever all the way to the end of the slot. You might feel resistance, but you need to keep slowly pushing, then when it reaches the end of the slot release the lever.

If it's VERY hard or impossible to push, then the valve is seized.

Customer: replied 1 year ago.
There is resistance.
Customer: replied 1 year ago.
it comes back the same point

OK that's good so far - valve not seized.

The next test is to create a demand for hot water at the programmer. If you already have, then I would suspect the motor in the valve, and the next stage would be to use a multimeter to verify that.

Customer: replied 1 year ago.
I put on the water heating which takes an hour . I ll let you know if there is any change in hour.
Customer: replied 1 year ago.
Hey we have a hot water now , thanks so much . So what was the real problem? Has it been sorted permanently u think?

Hm. Somehow I doubt that it has been sorted permanently. These things have a habit of rearing their head again. However, I'm glad that you have hot water!

I suggest that we leave this open - it won't automatically be closed for about a week. If you have another problem in that period then just continue posting here.

In the meantime, if you're happy with my assistance, please rate me using the 5 stars at the top of the page. This rating enables me to earn for the time I spent helping you.

Tim JA and other Home Improvement Specialists are ready to help you
Customer: replied 1 year ago.
You deserved more than 5 stars �� . Thanks a lot

Thank you for your rating and your kind words :-)