Hot Water Too Hot

[goldbyron]

Hi

Just trying to figure out a problem with our hot water. The water is coming out very hot all of a sudden. We have a baxi boiler and HW cyclinder system. I have done one test so far and turned off the CH and left the HW on. I experimented with turning the thermostat down to below 60 and the HW responded by turning off etc so this seems to work in isolation. I am wondering if it is the valve but I am not sure what I am looking for here? The CH thermostat also seems to be working fine in isolation. Is it possibly that the HW continues to heat whilst the CH is on? If so how would I check this is the case?

BTW not sure if it is relevant but also been having what I think are air blocks on one bathroom hot tap. Every few weeks for two months the HW runs low on one sink HW tap only (not bath or other bathroom). This seems to resolve itself when I run the HW tap in utility room. This tap will splutter for a minute or so and then runs fine, suddenly the bathroom tap works too. This may be a separate issue and just an air block but thought should mention it....

Thanks for any advice...

 

[Whitespirit66]

Assuming you have a 3 port motorised valve?

With the whole system cooled down, turn heating only on. Feel the pipe from port 'B' of the motorised valve that runs to the side of the hw cylinder. If this pipe gets hot, your valve is faulty.

Won't be linked to other airlock fault.

 

[goldbyron]

Yes it is a three port motorised valve. Only know this as it broke last year (about 12 months ago!) as it was clogged with sludge in the system. Sludge may have returned....

I will give it a test tomorrow and report back what I found. I think this sounds like the likely fault though...thanks

 

[Hugh Jaleak]

Not a Sunvic valve by any chance?

 

[goldbyron]

Hi

I will have a look tomorrow but don't think it is. Does this make a difference at all?

In meantime have set HW not to come on in morning and CH only so will know if valve is faulty by 8am...

 

[goldbyron]

Hi,

Well it seems the valve is at fault. I turned the HW off and had CH only to come on this morning for two hours. Lo and behold the CH was firing away and so was the HW (port B nice and toasty). As the heating is only on for two hours the HW was normal temp so obviously only gets scalding in the evening when it's on for longer. I am assuming that the valve is not going over the CH port only. Does this mean the whole thing needs replacing or could it be a wiring problem only?

It's a Honeywell valve as well. Only changed it twelve months ago, do these things break a lot??

Probably get a plumber out next week as dishwasher is priority this week (it broke two weeks ago but was over fifteen years old). Is there anything I can do in the evening to keep the temp down for now on HW? I have turned it to 50 on the thermostat if it makes any diff and turned HW onto OFF.

Thanks

 

[75pete]

Check that the Stat on the hot tank is in place and not hanging off.
Parts are available for the valve, do a search you will see.
Does the tank stat "click" when you change it's settings?
The valve should have a manual leaver on its side. With the power supply off, move the leaver and see if the spring return works.
Try the above
Pete

 

[goldbyron]

Stat on hot tank all fine. It's in place and clicks when I change the setting but this only works when HW is on and CH off. When CH on the HW doesn't respond to the stat on the tank.

I can see the man lever. I very much an amateur so not sure how to turn power supply off? I am assuming when power is off I move the metal bit along to man and it should spring back of its own accord? What would this indicate?

Thanks

 

[Hugh Jaleak]

Sunvic valves are renowned for failure, the Honeywell usually give a far longer lifespan. Sludge may well cause premature failure of a lot of the components in your system, (inc the boiler!).

You indicate sludge may have been a problem with the last failure and may have returned! What (if any action) was taken 12 months ago regarding system corrosion?