Do we want a combo boiler ?

[OneFrenchEgg]

Currently gravity fed system, 15 years old. Coming out this week to give an idea (boiler people).

Biggest issue is heating the water for four hours ish a day (am and pm) and then adults on shift/lazy/going out not having water because they are showering at the wrong time or after everyone else.

Due to CoL, and disability, five adults and one teen living here.

Radiators all fine, some have been updated more recently than others but all within the last five years.

I prefer things that are simple and have less to go wrong.

I like having a hot water cylinder that works even if the boiler needs repair (once in 15 years so far)

I like having a boiler that doesn't stop working if it loses pressure (because it doesn't)

I like having a gushing hot bathtap that is unaffected by anyone running taps or flushing toilets.

I like having no urgency or significant inconvenience if the boiler breaks down (see above)

A new system boiler will be so much more efficient than your old one. Makesure they know you have high hot water demands as they should quote for a slightly larger boiler. In terms of timer programmers most are twice a day but the more complex can hand 5 times a day so it can be programmed to heat water at specific times and it will heat a tank of water quickly
I have had combi boilers and not had any issue with them as well.

Ok.
So I'm assuming they aren't invested in selling one over the other.
I have BG cover and they've been great so far (in case things go wrong).

Pros:
Additional storage space
Hot water on demand (although cool at first as it heats)
No tank lurking in the loft

Cons:
Where to dry wet towels ?
Heat and water affected if an issue
I don't understand the topping up pressure thing
Baths might not be hot enough

A combi boiler can be quicker to install, meaning more jobs per week, which might mean quicker profits.

A lot more parts are inside the case.

IMHO, combis don't work with a power shower. Water pressure is something to consider. I also had the problem if the shower water running cold if someone turned a kitchen tap on, and you couldn't have two showers going at the same time ... so the ensuite shower I installed where the cold water tank had been couldn't be used at the same time as the family bathroom.

Ok less love for combis now.
Am starting to worry about it.

The pressure thing is not a big deal.

You have a tap that you turn on to let water into the heating loop and you have to do it periodically to repressurise the system.

The reason people have issues with it is because they hardly ever need to do it, so when the boiler stops working they haven't a clue what to do or what to turn.

The person who make the point about having a backup heater in the hot water tank - that is a valid one. Most people don't know about this either, but nearly all hot water tanks have an electric heater than can be used to get hot water even if the gas boiler fails. These are an expensive way to heat water, but great in an emergency if your boiler breaks and cost little money.

Maybe the best strategy is to detail all your requirements and then talk to an installer. I found BG very helpful and discussed a number of things with them via email before the install that I was concerned about and their person was very good at answering my questions.

I feel like the back up is less of a worry for me; we have boiler cover and priority etc. they use the immersion as a quick fix which annoys me.

My DM got a combi and it was no end of trouble. pressure dropping and plumber frequently needed.
I insisted on keeping a hot water tank when our 30 year boiler died. We have oil central heating which heats the water. Plus a back up immersion heater, plus an electric shower.
Our immersion heater gets used a lot since we got solar panels and a fluctuating tariff (Octopus Agile).

We don't have boiler cover as we use a local plumber, so backup is more important to us, when the old boiler packed up in December and it took about three weeks before it could be replaced we were extremely glad of the immersion though.

Even a couple of days without hot water would be a trial.

A week or more would be severe.

It's a Potterton Promax Ultra. Or as I call it, the prick in the kitchen cupboard.

I don't understand how they work but basically if the pressure drops, the boiler will not fire up. Various crappy parts breaking problems can cause pressure to drop.

When this happens you have to top up the water in the boiler to bring the pressure back up and reset it to get it to fire up. This is not a fix, pressure will keep dropping until its fixed. Which if you're my housing association, may be several months away.

Drives me absolutely batshit crazy.

I would kill for a tank and immersion right now. We've been playing guess which part is most crap since mid December and still haven't got to the bottom of it.

@Balloonhearts do you mean literally? Like with a jug? I feel like I need to rethink my plan.

No there's a little tap underneath it so you stick your head underneath and look for the pressure gauge and the two little blue taps. Mines the one furthest to the back so you open up the little tap and it fills, keep going until the gauge goes up to about 1.5 then close it and hit reset.

It's not difficult but it's a pain.

The pressure drops on mine but I only have to deal with it like once every 4 months. If it was more often I'd worry about a leak but for that it takes me 10 seconds, if that, to get it back up and running.

The first time I panicked and once I realised it was broadly normal and could very easily be sorted I stopped worrying.

If I was organised and just checked the pressure every 3 months like I do with my car and bike tyres I'd never have the problem.

My pressure gauge is on the front so it's super easy.

Ok pressure sounds less technical than I thought.
Have a load of questions.

I much prefer having a hot water tank. It means we still have hot water should the boiler pack up (which it has on several occasions over the years).

I switched to a combi boiler last year.

I had an absolute nightmare with my heating over a long number of years, and various plumbers promising they'd fixed it & hadn't.

The combi boiler, while a lot more expensive than the system boiler, was initially a godsend. (The actual installation was hell, lots of issues with blocked pipes were uncovered & it took ages & required replacement of pipes to resolve it.)

I've 3 teens so the instant hot water was great. Heating brilliant.

A yeah on the last few months has been very problematic & I'm less than happy

My h/w temp has really dropped in the last few months; plumber argues there's no great issue but it's not hot enough to wash dishes, and showers are tepid. It's driving me mad.

The water pressure drops frequently - apparently there's no leak but I'm concerned.

The other issue as PigletJohn mentions is that if the boiler isn't working, you've no hot water. That's been a real pain.

Overall I like it still but I don't like that when there are issues no one seems to know really what's happening.

No, it's not technical but it shouldn't happen. Re-pressurising can introduce sludge into the system (essentially what my original problem was, necessitating a new boiler).

"My h/w temp has really dropped in the last few months; plumber argues there's no great issue but it's not hot enough to wash dishes, and showers are tepid. It's driving me mad."

The last few months have been winter, so the incoming water has been colder.

It is characteristic of combi boilers that "hot water" will be less hot in winter.

If the boiler can heat, say, 12 litres of water per minute by, say, 30 degrees, then in summer your incoming water might be 15C and you hot bathtap 45C. But if in winter your incoming supply is 5C, your hot bathtap will be 35C. The boiler is continuing to increase the temperature by 30, so it is performing to specification, but your bath is not as hot. You could run the bathtap slower, so it delivers 8 litres of water. It might then take ten minutes to run a bath, instead of six.

If you have a hot water cylinder, the boiler can heat it to 55C summer and winter. It will fire for a bit longer, but you will not notice it, because it prepares your water in advance.

As an update, we have decided that we are moving to a combi. Really grateful to everyone as I asked lots of questions, especially the shower etc. it may be the wrong choice but it feels informed. Boiler change will release kitchen space by moving to airing cupboard and so towels can still dry. We really will value having additional loft space as well.

The last few months have been winter, so the incoming water has been colder.

I know - I checked that out. But it was also winter 12 months ago & no issue then! Piping hot water.

Also - it's variable. Sometimes it's warmer or colder in the shower. Never more than tepid in the sink (yes, obv mains water but it's like that when cold outside or not eg fine during snow / ice pre-Christmas, not so in an exceptionally mild spell in January.

I had read the details you posted in my extensive googling to understand it!

But it can't be the whole story - why would the water have been hot for a year, then over a few months get tepid to the point it can't be used for dishes? It needs 3 kettles of boiled water added to make it usable. That's not normal!

Why would the shower be warm / tepid / nearly cold (within the same shower) but never very hot, even at full capacity? (The shower may have other issues as it was a power shower installed just before I got the combi boiler so they were able to adjust the 'power' aspect so it was usable but I'm not convinced it works very well.

At some point I plan to replace my very old bathrooms so would address this then. But that's some way off.

Best of luck. I'm still happy about a combi - the instant h/w (when we have it!) is a game changer with kids.

I would say that be prepared for the massive inconvenience if anything goes wrong. My plumber is very good at coming out but we've had several days without it sometimes & that's a nightmare with no hw for showers / cleaning. Whereas no heating is copable with for a few days, with a few portable / plug in rads + fire maybe.

Get a decent brand (We have a Vaillant but I'm pretty sure there's one that's even more reliable). and an extended warranty

When I had mine out in 6 years ago the difference was amazing compared to the old knackered boiler we had that kept losing pressure etc

I just got mine repaired 3 months shy of the cut off date thanks to my lovely plumber who'd chosen the extended warranty which I didn't even know

Often when you think it's not working you just need to change the battery in the thermostat- make sure you get a new one of those - mine you can set to loads of different times and temperature and it's so so easy to set up and use - very user friendly

Our shower heats its own hot water so if the boiler goes we can still shower, use the washing machine and dishwasher