Boiler/hot water problem - advice please

justontime

We have a Valliant Ecomax condensing boiler (not combi type). It was fitted in Nov 03 and has been serviced annually, we had new radiators at the same time. We have a hot water tank in the airing cupboard and if we don't want to have the boiler on we can heat that tank with electricity, it plugs into a socket in the airing cupboard. I am unsure of the age of the water tank, but it is at least 16 years old.

Just over a fortnight ago our hot water stopped working suddenly. It hadn't been gradually getting cooler, if anything it was too hot. The boiler and the central heating still work fine, but even the electric heating didn't heat the hot water. There was a delay sorting it out as the first plumber messed us about. We noticed that sometimes the water was slightly warm, then one morning it was back as hot as it used to be (and I had a wonderful hot bath) it hasn't got hot again since, just tepid sometimes. The boiler man came today and said he had checked everything and had ruled out other problems so the only possibility is the tank, he said the coil must be totally clogged so that is not working. He has quoted for a new tank and we have arranged for him to do the job next week. I just wondered anyone could tell me if this sounds plausible please. I have been ripped off by a plumber in the past and it has made me much more cautious since then. Thanks

Canucklehead

Hi

Do you have one or two valves that look like this in the cupboard with the cylinder?
http://www.uk-plumbing.com/honeywell-v4043b-1265-2-port-28mm-zone-valve-p-1407.html

Corgi Guy.

justontime

Canucklehead wrote: »

Hi

Do you have one or two valves that look like this in the cupboard with the cylinder?
http://www.uk-plumbing.com/honeywell-v4043b-1265-2-port-28mm-zone-valve-p-1407.html

Corgi Guy.

One (put in at same time as boiler) Plumber said the valve is working because pipe is hot one side and cold on other. Thanks

Canucklehead

Hi

Do you mean that there is only one valve in the cupboard and it is connected to the cylinder.? Or is it 'T' shaped, with one pipe going to the cylinder.
If it's working it should be hot on both sides.

The test is to have the system running with both c/h and hot water calling for heat.The small lever on the end of the valve where the cable is should move freely from side to side along the entire length of the slot. If there is resistance and you need to push it firmly to the end of the slot (when you let go it will spring back) then it's not working properly.
It would take a lot of scale to totally block a 28mm pipe (that's the diameter of the pipe in the cylinder) I'm very suspicious of the need of a new cylinder.

Corgi Guy.

plumb1_2

very unlikely the coil is blocked, more likely the 3 way zone valve.

justontime

It is just like the one in the picture, there is a middle pipe that seems to come from the boiler then one pipe leads to the tank and one leads down under the floorboards. All three pipes are hot. The plumber said he thought it was the coil in the cylinder. There is no resistance on the thing you said should push all the way along, it moves easily. All pipe work outside the cylinder is new (2003).

justontime

Someone else said it could be a diverter valve, I don't know what that is, but is it likely to be that?

Canucklehead

Hi

The valve in my link is a two port motorised valve. You have a three port motorised valve, AKA diverter valve .

Are there any valves on the pipe that comes out of the cylinder about 18" directly below the one from the one going in (with the valve on it) It might be a red handled gate valve or maybe a red /yellow lever type. Is this pipe hot as well .
The three way valve would be the first thing I would check .

Corgi Guy.

justontime

Canucklehead wrote: »

Hi

The valve in my link is a two port motorised valve. You have a three port motorised valve, AKA diverter valve .

Are there any valves on the pipe that comes out of the cylinder about 18" directly below the one from the one going in (with the valve on it) It might be a red handled gate valve or maybe a red /yellow lever type. Is this pipe hot as well .
The three way valve would be the first thing I would check .

Corgi Guy.

The pipe with the three port motorised valve goes into the boiler about 12ins from the bottom, there is a pipe that comes out about 8-10ins below that, it comes out for a couple of inches to a joint and then goes down through the floor; at the top of that joint there is a blunt end sticking up about two inches from the joint with a valve like the ones you get on the type of radiators that you bleed with a key. This pipe is cold. There is no red handled gate valve or red and yellow lever valve or anything similar. On the other side of the cylinder there is a pipe running down from the loft to the base of the cylinder, I assume this carries cold water from the tank in the loft. There is also a pipe coming down the centre back of the airing cupboard and jointed to lead into the top centre of the cylinder, this is cold but not cold like the one that seems to be bringing cold water into the cylinder. There is a narrower pipe sticking up at the back with a black valve with a red cap like thing, I believe this is the means of releasing excess pressure. There is also a flexible pipe at the back with a lever valve thing to allow us to top up the pressure when necessary, it is right behind the cylinder so I can't see it, I can only feel for it.

Thanks for your advice.

Razor

Hi,

A picture would be great if you can manage it, from your description I would suspect an airlock in the cylinder coil the coils themselves do not block with scale, at worst inlets and outlets on cylinder can scale up but they are relatively easy to clean certainly not a reason to replace.

If there is no airbleed on the pipe that goes from the 2 port valve to the upper connection of the cylinder I would turn it all off and very carefully loosen , not undo),one of the nuts and see if any air comes out.

ps piccys really do help.

justontime

This is the best I could do, it is not easy to take photos in such a cramped area. I hope this is OK.