What type of C/Heating boiler should I have installed?

TUVOK

My existing C/heating boiler is the original build boiler in 1995, it has always been working ok and for at least the last 10 years it has had a service by a reputable firm.
It had a service last in November 2024, about a month later it started to fail to ignite on the central heating part, the engineer came to check it and said unless something totally failed it was extremely difficult to say what the problem was.
On hopefully understanding that it was likely to be either the room thermostat, the Drainton timer or the diverter valve I opted to replace the Drainton timer.
The time settings were set in to the new timer but about once a week the same problem occurs in which the c/heating will not fire, it's usually been on a cold day when the boiler has been in c/heating mode since early morning.
As the boiler is now 30 years old and most probably not as efficient as a new modern boiler and as I am now nearing 80 years old, I cannot take the hassle of trying to get it to fire and having no heat in my house, I have decided to replace it.
My engineer has said that a combi boiler would be a total bill of about £4K and a replacement existing type boiler about £3300-00.
There is only my partner and myself in the house, we are not heavy gas users according to OVO figures, any advice on what type of boiler to go for, Combi or existing type.
Any help/replies would be much appreciated. 

FreeBear

TUVOK said: As the boiler is now 30 years old and most probably not as efficient as a new modern boiler and as I am now nearing 80 years old, I cannot take the hassle of trying to get it to fire and having no heat in my house, I have decided to replace it.
My engineer has said that a combi boiler would be a total bill of about £4K and a replacement existing type boiler about £3300-00.
There is only my partner and myself in the house, we are not heavy gas users according to OVO figures, any advice on what type of boiler to go for, Combi or existing type.

£4K for a replacement combi isn't too bad. £3300 for a straight swap of a system boiler is a bit high in my opinion unless it includes having to move it to a different location and/or includes a new (well insulated) hot water tank.

Regardless of which you go for, I'd recommend a few additional upgrades -

• Larger radiators in most of the rooms that you use.
• A programmable thermostat that allows for different temperatures to be set during the day/week (should be fitted by default).
• A boiler that has a decent modulation range and can go down to 3.2kW (Greenstar 4000 or Viessmann will).
• Pick a boiler that has OpenTherm - This opens up the range of compatible thermostats/controls consiserably.
• For a system boiler, you only need 12-18kW maximum. A combi should be rated for cold water flow rate.

Fitting larger radiators will bump up the cost, but does mean you can run at a lower flow temperature. This is essential to get good efficiency. A side benefit is it reduces the risk of burns should you come in to contact with a radiator. An important point with young children and the elderly.

I'd also suggest getting quotes for a heat pump (Octopus, EDF, EON, and Ovo all advertise them). You may well find that the price for a heat pump is very competitive when compared to a gas boiler + bigger radiators - A heat pump requires bigger radiators and a new hot water tank by default, so the quote might appear to be higher initially. When I was looking at replacing my old gas boiler, a combi was around £2500, and Octopus was quoting me about £2700.

I ended up spending £500 (give or take) replacing radiators & plumbing on top of the £2500 for the combi (Viessmann 050). A heat pump from Octopus would have included the radiators....

TUVOK

FreeBear said:

TUVOK said: As the boiler is now 30 years old and most probably not as efficient as a new modern boiler and as I am now nearing 80 years old, I cannot take the hassle of trying to get it to fire and having no heat in my house, I have decided to replace it.
My engineer has said that a combi boiler would be a total bill of about £4K and a replacement existing type boiler about £3300-00.
There is only my partner and myself in the house, we are not heavy gas users according to OVO figures, any advice on what type of boiler to go for, Combi or existing type.

£4K for a replacement combi isn't too bad. £3300 for a straight swap of a system boiler is a bit high in my opinion unless it includes having to move it to a different location and/or includes a new (well insulated) hot water tank.

Regardless of which you go for, I'd recommend a few additional upgrades -

• Larger radiators in most of the rooms that you use.
• A programmable thermostat that allows for different temperatures to be set during the day/week (should be fitted by default).
• A boiler that has a decent modulation range and can go down to 3.2kW (Greenstar 4000 or Viessmann will).
• Pick a boiler that has OpenTherm - This opens up the range of compatible thermostats/controls consiserably.
• For a system boiler, you only need 12-18kW maximum. A combi should be rated for cold water flow rate.

Fitting larger radiators will bump up the cost, but does mean you can run at a lower flow temperature. This is essential to get good efficiency. A side benefit is it reduces the risk of burns should you come in to contact with a radiator. An important point with young children and the elderly.

I'd also suggest getting quotes for a heat pump (Octopus, EDF, EON, and Ovo all advertise them). You may well find that the price for a heat pump is very competitive when compared to a gas boiler + bigger radiators - A heat pump requires bigger radiators and a new hot water tank by default, so the quote might appear to be higher initially. When I was looking at replacing my old gas boiler, a combi was around £2500, and Octopus was quoting me about £2700.

I ended up spending £500 (give or take) replacing radiators & plumbing on top of the £2500 for the combi (Viessmann 050). A heat pump from Octopus would have included the radiators....

Thank you for your comments on 'additional upgrades' I'll be researching those.

ThisIsWeird

Hi Tuvok.
As FreeBear says, the combi cost sounds in the correct ballpark, as it's more involved - system changed to unvented/pressurised, and hot cylinder removed, etc - but the new 'Heat-Only' boiler replacement cost sounds pretty high.
There could be reasons for that, say the flue needs a complex route, or taken through a roof, for example? Where is the current boiler located?
Another potential complexity is the need for a condensate pipe - again if the route for this is complex - but that applies equally to both boiler types. Currently, the Combi price seems ok, but the H-O is high.
Does everything else work fine? Plenty hot water flow from your taps? Happy with it all - except the unreliable boiler? If so, I'd personally look for a few more quotes for H-O boilers, and see if you can get one for around £2.5k. That should be the typical figure, unless there's some particular complexity with yours.
As for the other stuff - larger rads, etc - you will never get a return on that outlay. It's bonkers. Leave that to the next owner of your house, and whatever heat sources are available then.
Make and model of your current boiler? The reason it's still largely going strong is because it is simple - it's a metal container with water inside it, and a gas fire underneath. Everything else - the pump and the diverter valve - is mounted externally.
Your issue is that, sometimes it doesn't fire up when calling for CH? As you say, the most likely candidates for this issue are the timer, the wall stat, and the diverter, and - of these - I'd be giving the diverter a very stern look. 
The timer - programmer - has a wee light on it when the CH (or DHW) is timed to be on, yes? If so, the next time the boiler fails to come on, check that light. Is it 'on'? If yes, then most likely your timer is working fine. 
The wall stat - I'm guessing it's a basic dial type you turn up and down to the desired temp? If so, the next time your CH fails to come on, turn the dial up and down a few times and check it solidly 'clicks' at around the current room temp. Does it? Then almost certainly it's working fine. They rarely fail, and if it's a bit temperamental, then your clicking should prompt your boiler to fire - does it?
The diverter valve, tho', well, they are very prone to sticking after a decade's use, and this will mean it won't switch on the boiler - there's a wee switch inside it that's activated at the end of valve travel (eg, when it's moved to CH position), and if the valve doesn't quite get there, or the switch is sticky, then your intermittent-firing symptom is pretty darned classic.
Fortunately you can test this component quite easily. Do you have a shoe? Cool - hit the metal case with it the next time you've asked for CH but didn't get it. A nice firm thunk, repeated if necessary, but obviously don't go silly. If the boiler then fires up, you need a new diverter valve, possibly just the 'head', but best replace it all.
Because, your very best option is to keep your current boiler running for as long as possible

Albermarle

When comparing a Combi with a system with a hot water cylinder, there are a few things to think about.

Normally for a smaller household, a combi is recommended as your need for hot water is probably not great. Although you need a minimum mains water pressure for it to work effectively.
You can get rid of the hot water tank, so make more space.
The downside is that if the boiler breaks down you will have no hot water at all, whereas now you can still heat the tank, assuming there is a back up electric immersion heater fitted ( there normally is).

Section62

TUVOK said:

...
It had a service last in November 2024, about a month later it started to fail to ignite on the central heating part, the engineer came to check it and said unless something totally failed it was extremely difficult to say what the problem was.
...

You perhaps ought to start by changing your heating engineer rather than changing the boiler.

A competent person should be able to fault-find in an old-style heating system without too much difficulty.  Intermittent faults are harder to trace, but the simplicity of old controls gives you limited options as to what is wrong.

If the boiler works Ok for hot water and the fault is only on the CH side then it would be incredibly unlikely the boiler is faulty as a non-combi from 1995 doesn't 'know' whether it should be providing central heating or hot water, it is only interested in whether it should be on or off.  I.e. if the hot water works flawlessly then the fault is somewhere other than the boiler.

As per ThisIsWeird's post, the diverter/3-port valve (or a zone valve) is the usual suspect if one is fitted to the system - in most setups the valve controls when the pump runs and when the boiler comes on.  If the valve goes wrong it won't tell the boiler it should be on, and the boiler won't fire.

Provided the timer and room thermostat are providing voltage when they should be (and having replaced the timer they ought to be), the engineer should have suggested changing the valve.  At that age it is probably worth changing the whole valve rather than just the actuator head, at the cost of about £60 for the part +labour.

If you do end up replacing the boiler - and do so like-for-like rather than going combi - then you'll need a functioning 3-port valve anyway.  So the parts cost would only be wasted if it turns out the old valve was fine and/or you go for a combi instead.

MysteryMe

Costco do a supply and fit of a Worcester Bosch 2000 25kW Combi Boiler for £2300

Olinda99

I went for an Octopus heat pump - they changed all the rads, installed heat pump, took away old cylinder and tanks in loft, old boiler, gas meter-  all for less than a new replacement boiler. Also now no gas standing charges !

ThisIsWeird

Olinda99 said:

I went for an Octopus heat pump - they changed all the rads, installed heat pump, took away old cylinder and tanks in loft, old boiler, gas meter-  all for less than a new replacement boiler. Also now no gas standing charges !

Blimey! That's a cracking deal!

How did you manage this?

MysteryMe

Indeed, as no price was given, it's difficult to assess what kind of deal it was or indeed type of heat pump. I doubt it's less than the cost of a combi I gave an example of.