Need to replace 40 year old boiler and need advice to understand what I am being told

[Littlemoney]

In 1983 a Potterton Kingfisher floor standing boiler with pilot light and central heating system was installed. It's gravity fed with hot water tank. The radiators have TRV's which don't seem very responsive to temperature changes and the only thermostat in on the boiler and for heating/water there is only a timer system. The boiler on an internal wall and fumes go up a chimney.

Last two times I heated the hot water for a bath it was only luke warm. When recently I checked the radiators on first use since the spring. Radiators heated up ok but after short while I noticed water coming from overflow pipe in loft which was warm. The expansion/feeder tank was hot and the adjactent cold water tank was warm. So no hot water and no heating.

Had a local business come to investigate saying it might be the coils in the hotwater tank, though I don't know what this means. Was informed would need new tank and not sure if they could be one for a gravity fed system with only a pump for the heating system and I would be better replacing the boiler and all the radiators as due to age when they flush the system there may be leaks.

I had been thinking about getting a replacement boiler prior to this but need to know more about what to look for and what questions to ask. There seems to be so many options in boilers, radiators types and sizes. It is a 70 year old detached 3 bed house, 1 bathroom and 1 occupant who does feel the cold now and is spending more time in the house. I am trying to learn so I don't get taken for a ride and get ripped off. Where do I start? I am feeling the pressure with winter coming and no heating and no one to ask. Thanks for reading.

 

[Madrab]

I must be honest and suggest that it sounds like the system has seen better days. Given the system is feeding back into the expansion cistern and the fact the the cold water cistern is also warming up suggest that it isn't happy.

Without being on site it's practically impossible to say whether the system is salvageable or whether it may be better to replace rather than repair. If the whole system is over 40years old then it could certainly do with an update - not to say a 40yr old system, well looked after can't carry on for another 40years, but this one doesn't sound like that.
How extensive that update may need to be would really be best considered by a reputable recommended independent to survey and see what if anything could be salvaged.

 

[muggles]

Don't get rushed into a large capital purchase by a company who are short of work. It's the busiest time of year for the industry and companies who are available almost immediately to do this kind of work should be viewed with suspicion.

If you were my customer I'd be suggesting we fix the immediate problems immediately, and look to do the full system works in the New Year, probably once the weather improves. If nothing within the system has been changed then the pumping over issue should be relatively easy to sort. At worst, yes you might need a new cylinder, in which case do that now and sort the rest of the system later. Gravity coils cylinders are very much still available and can be used on fully pumped systems too.

 

[Notch7]

not sure if they could be one for a gravity fed system

So you currently have a system which has large diameter pipes going from the boiler upto to the hot water cylinder. When the boiler comes on it heats the water in the pipes which makes the water rise up as hot water is less dense than cold, that’s what creates the water to circulate…..for this to work well you need fairly large pipes like 28mm and the coil inside your cylinder is part of that circuit so the coils needs to be quite large diameter too.

But you can still buy such cylinders.


I was in this situation earlier in the year, having to replace a 40 year old boiler. I was lucky an found a really helpful local plumber who gave me lots of sound advice.

My plumber recommended either an Ideal boiler or a Baxi / Main (Baxi and Main are same boiler really). I did lots of research and found these are generally quite liked by plumbers, they are basic boilers but well made, lots are fitted so parts are readily available and they are easy to service.
Bosch / Worcester boilers are very common, but reviews I’ve read say lots of plumbers aren’t too keen….complicated to service and cheap plastic parts.
Don’t worry too much on boiler make, I’m sure any boiler fitted well will work very well. Bear in mind European brand boilers like Viesseman and Vaillant aren’t as well supported for parts and technical

My radiators were all 40 years old so I got them replaced as well, like you.

I had a gravity fed hot water / pumped open vented heating like you and I chose an Ideal vogue system boiler which uses a hot water cylinder tank for the hot water, the heating is pressurised and doesn’t need the expansion tank in the loft.

I also had a hot water priority layout which is quite simple which I can recommend very much - perfect if you spend much time in the house, it basically has 2 temperatures, a high temperature which heats the hot water, then a much lower temperature to heat the central heating, this Ive found fantastic, we have the central heating flow temp at around 38 to 45 deg, which provides a gentle heat to the house and we now have the heating on for long hours but it uses very little gas. (The actual flow temperature is set by measuring external temp, so the system will use hotter radiators in colder weather to make sure the house gets warm enough)

 

[Littlemoney]

Don't get rushed into a large capital purchase by a company who are short of work. It's the busiest time of year for the industry and companies who are available almost immediately to do this kind of work should be viewed with suspicion.

If you were my customer I'd be suggesting we fix the immediate problems immediately, and look to do the full system works in the New Year, probably once the weather improves. If nothing within the system has been changed then the pumping over issue should be relatively easy to sort. At worst, yes you might need a new cylinder, in which case do that now and sort the rest of the system later. Gravity coils cylinders are very much still available and can be used on fully pumped systems too.

Noting in the system has changed. Only noticed an issue with two lukewarm baths and a subsequent test of heating before winter when I saw water coming from the overflow pipe and went to the loft to check and found a warm cold water tank.

Did a short run of central heating this morning to see if issue still occuring. The only difference being the one radiator without a TRV was more open than ususal. That radiator got very hot and the boiler kept firing up frequently even when the TRVs on the other radiators were decreasing the flow and had reach the right temperature. After 45 minutes switch it all off, no sign of water overflowing but non TRV radiator still very hot and was concerned. This radiator didn't used to get hot like this

Hot water was now hot enough for a bath, so I did. I havn't yet checked if hotwater only heating gives hot or lukewarm water.

 

[Littlemoney]

So you currently have a system which has large diameter pipes going from the boiler upto to the hot water cylinder. When the boiler comes on it heats the water in the pipes which makes the water rise up as hot water is less dense than cold, that’s what creates the water to circulate…..for this to work well you need fairly large pipes like 28mm and the coil inside your cylinder is part of that circuit so the coils needs to be quite large diameter too.

That's what my system is. I can't have heating on without hot water on.

Why did you go for a system boiler. In the summer I was thinking about replacing the heating system especially as my only control is a clock and I have to guess when getting home and sit in a cold house if home too early. Unfortunately health issues prevented following up at the time. The quote was for combi boiler, as thats all I had heard of, and they install Ideal boilers

 

[SpecialK]

Have they checked your mains pressure and flow rate to make sure it is suitable for a mains fed boiler?

By fitting a combi you would be without a water tank which might give you some extra room? A lot of combi boilers are very large and struggle to ramp down their heating power to get low flow rates.

If you like high flow showers an unvented tank system would be great with a seperate boiler?

 

[Hugh Jaleak]

Existing system is fairly simple, as was the norm at the time. The Hot Water Cylinder relies on gravity circulation through 2 large pipes, that must rise continuously from the boiler to the cylinder, one is flow, the other returns the cooled water once it has passed through a coil inside the cylinder, whereby the heat is transferred to the stored water within the cylinder, which then feeds your hot taps.

The Central Heating then is operated by means of a Circulator (Pump), that sends the heated water from the boiler around the radiators when the Central Heating is switched on. At the very least I would be looking to add a Room Thermostat which will switch the heating on/off as the temperature in the property requires, should be fairly easy to add to what you have, it's only additional wiring.

If you're looking to modernise on a budget, it may be possible to adapt the system with a new Boiler, pipework alterations and new controls, I had the same boiler and swapped mine over without difficulty, it all depends what you want to achieve going forward and what your finances will stretch to.

 

[Littlemoney]

Thank you all your explanations and advice. Right or wrong I've decided on a combi boiler. I have other questions but I will start a new thread as they relate to the new system.