Home Improvement Questions? Ask a Handyman for Answers ASAP
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.
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?
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?
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?
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.
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.
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?
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.
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.
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.
Thank you for your rating and your kind words :-)