Boiler under sink cupboard

[rainbow2]

My elderly widowed father has a hot water boiler, no central heating, which is in a cupboard under his kitchen sink. I think the boiler is on its way out now as the water is extremely hot (scalding in fact). The problem is, I don't know whether he should just pay to get it serviced (it was last serviced 2 years ago - this helped the temperature a little but then it went back to scalding soon after), or to just buy a replacement. He is 80 years old and obviously on a budget, but not on any benefits. Would he be throwing away good money by getting it serviced again or should he just opt for a replacement? He is concerned about replacing it though because he thinks they will not put a boiler under the kitchen sink any more. He lives in a very small bungalow and we're not sure where they would want to put it. Does anyone know ?

[buildersmate]

What fires this thing? - gas or electricity? I assume electricity because every gas appliance requires a flue (and hence access to an outside wall) and you make no mention of this.
If electricity, then a relatively simple thermostat drives the point at which the heating device turns off. In which case the issue may be to do with clogging of the element with hard water scale - preventing the thermostat from working properly. Does your father live in a hard water area?
Please provide a bit more info. Heating devices driven by electricity are generally very reliable and apart from the issue above do not need servicing much. They are not however cheap to run in energy costs.

[rainbow2]

Thanks for your reply buildersmate. I should have made clear that it is actually a gas boiler and the flue is on the outside wall of his kitchen, just behind the sink. He does not live in a hard water area. I've noticed that British Gas are doing a limited offer of �49 for a service, instead of the usual �79, but like I said, I'm not sure that a service would solve the problem.

[buildersmate]

Then what happens if you turn the boiler temperature thermostat dial down? Surely it has one of these? Or is this a direct heater that just fires up when he wants hot water (the modern version of the old Ascot heater). If the latter, then its the cold water feed at fault - you get the water temperature down by turning up the water flow rate. This reduces the time a unit volume of water gets cooked by the boiler. Result - cooler output temperature.

[rainbow2]

Thanks for replies. The boiler is one that fires up when he wants hot water. It has two positions on it - a 'winter' and a 'summer' - neither seem to make his water any colder.
When you said , buildersmate, that the cold water feed could be too low, does that mean he should turn up the water pressure himself? Or does it mean that a gas fitter needs to do something to the boiler?
i'm with you, cleversod, on your reply - I can see it costing him a damn sight more than �49 if British Gas come to it !

[buildersmate]

I don't know. What specific model is it? - or it is too ancient now to know. I'm just saying that that's how these Ascot-style heaters used to work. I'm summising that the water pipes are partially scaling up through usage (over time - same as happens in a kettle), reducing the water flow through it. That would make the water coming out the back end hotter. Maybe all the service engineer is doing is cleaning out the scale. Any more info you can provide?

[rainbow2]

It is a Main Medway automatic. Must be fairly old 'cos it was in his house when he bought it ten years ago. Sounds like maybe the service engineer might be able to fix it from what you say. Thanks for your advice.

[buildersmate]

Found this.
http://forum.plumbingpages.com/main-medway-vt3 30.html
Having read it, I'm pretty sure that it is scale that is causing this problem. As one of the technical guys says in reply, these devices produce a fixed amount of heat input. If the rate of water flow across the boiler falls (over time, due to scale build-up), the temperature of the heated water at the output will rise.

[gucciman]

main medways are still very much in use, we repair and service them on a regular basis.

the big problem with fitting them is main no longer make them, they contract the work out abroad and the new model is a lot longer than the original so you are probably not going to get it fixed under the sink as the pipework enters from the bottom and space would be very restricted.

if you could get hold of a second hand one from somewhere it would be a straight simple swop.

repair wise, i'm racking my brains to remember how the temperature is controlled, i'm not sure if they use thermisters or not or whether its controlled by a tap which slows or speeds up the flow of water over the burner.

are you anywhere near south birmingham?

and post this question in the main home and garden section as gasman will answer then, you get less answers in the property section

[rainbow2]

Thank you Gucci - my father is near Chester. I will ask in Home & Garden if the gasman could maybe read these threads.

[gasman]

Hi rainbow,
These boilers are simple to service and maintain. From reading through the previous posts I would think there is no need to replace the water heater, it does sound like the filter and heat exchanger is scaled up. The filter is easily cleaned up but the heat exchanger may need to be replaced but is easy to do. I would also change the diaphragm aswell as this needs changing every 3-5 yrs as part of a full service.
There is also no reason why he could not put a new boiler in the same place either if he does replace it.

[rainbow2]

Many thanks gasman. He will now get it serviced with the British Gas offer that's on at the moment.