In two minds about combi boiler

[PogoBob]

Old boiler (Ideal classic FF250 fitted in 1999) has finally died so looking for a replacement. Have a selection of local companies and BG lined up to come quote - first of whom came today and automatically went to the move to a combi boiler position and could not seem to see why I would want something else.

My concern with a combi boiler is the instant hot water issue or should I say lack of instant hot water, from what I have read and speaking to people who have a combi it's more water on demand with a time lag. I am also worried about water pressure as we get around 7.5 litre per minute on kitchen cold tap and an utterly pathetic dribble in the shower when the pump is turned off.

It's a 3 bed house, one bathroom with mixer shower with pump and 7 radiators. Suggested boiler is a Baxi 830 30 kw.

To add to my dilemma the current shower pump leaks, our three port value is broken and there are signs of seeping from one of the pipes in the airing cupboard. A combi boiler would resolve the above issues (assuming the water pressure was enough for the shower) whereas we'd have to pay out for those problems on top of a conventional boiler.

Really don't know what to do - am I being overly harsh on combi boilers here (have had serious bad luck without domestic emergencies recently so have lost all confidence!)

We has a worcester bosch combi boiler in our previous 3 bed 1 bathroom house And it was fine. Water pressure great for a shower and hot water on demand - never any problems and you can get rid of water tanks.

Thanks @bilbodog. It would help having that extra space I won't lie. I'm normally really decisive but hate making these types of decisions!

Worcester combi boiler, make sure the plumber takes out the old water tanks, hot and cold. Then you will also get more space.

Never heard of lack of instant hot water with a combi boiler. Strange that you've had 'people' plural telling you this.

Plus don't you have to get combis these days for the energy efficiency? Think of your EPC certificate when you come to sell!

Condensing boilers (a type of combi) are the new version of combis as they are more environmental. We had one fitted last year and it's brilliant. Water is piping hot though so I keep having to turn it down.
The only reason to have a traditional boiler fitted (IMO) would be if you have a very large house, but then you'd need two of any type of boiler so two combis would be just as good.

Removal of the tank and pipes is included in the pipes.

My mother has a combi and regularly complains about the water taking time to heat up, a colleague said similar when discussing last week and when I search here there are various threads complaining about the same issue (same when I google as well). I have no direct experience of combi boilers so can only go off what I have heard / read even if only anecdotal.

You need @Johnd or @Pigletjohn for advice.

Our combi has the option to hold a small tank of hot water 'at the ready'. I never have it on. The issue isn't much different to the hot water tank really - it is all about how far hot water has to go for tank/boiler to tap. If the boiler is near the tap then a short distance of pipe for water to cool down in.

Gas boilers apply heat pretty quickly from a cold start - there is a small delay but not much.

A bigger issue is whether the mains pressure is enough for a shower and water being drawn elsewhere (toilet flush, dishwasher, washing machine). I'm debating whether to go for a condensing boiler with a hot water tank, or a pressurised tank when we get ours replaced. We'll have two showers and preparing for teenagers! Currently the shower pressure drops when the toilet is flushed and a tap is run. Add another shower into that mix and another floor up and I think it'll be really bad.

As long as you have the correct size of combi for the amount of radiators and showers that you have in the house, then you are fine. Often people add extensions and more radiators etc and then the combi can't perform as well. (Maybe your mother should get hers serviced and checked?)

Obviously I know nothing about water pressures though!

My combi gave us instant hot water and the shower was amazing, we had a thermostatic valve in the shower so if the pressure dropped then the water temperature didn't change.

Your current shower is getting its pressure from the difference in height from the cold to hot tanks rather than mains pressure I suspect.

Get a megaflow system installed and all you worries will fade away :)

When moved to our new house it's much larger and on 3 floors so went for an unvented cylinder, we had the old mains pipes replaced that run from the water metre to the house to the current 22mm standard.

We live at the top of the hill and have mains pressure showers on all 3 floors and can have 2 running at once with no issue 🤷🏽‍♀️

Had a Vaillant combi boiler at my last house and it's the ONLY thing I miss! Loved the all-day supply of hot water on demand (so don't have to worry about having a bath and doing the washing up in one day) and the much cheaper energy bills as could keep the house warm without extortionate electric heaters.

We have a Worcester combi boiler and I love it. Occasionally it will run cold for a minute, if I’m doing a lot of washing up for example (boiler is very close to sink) but it soon comes through hot again. No problems with the shower going cold.

In most houses they are so fab! My bills were so cheap in our previous house.

There are downsides to living on a hill near the coast, amazing view and nearly always a breeze to dry your clothes though 😂

We've had Combi boilers in two houses.

They've been fine, but if you run a hot tap on a different floor to the boiler (eg boiler upstairs, tap downstairs) it definitely takes a while to heat up. We've had one boiler upstairs and one downstairs and had this issue in both houses.

@AKissAndASmile

No, you don't have to buy a combi boiler. You have to get an efficient, condensing boiler. Some of them are combis and some aren't.

An easy mistake is to think that the reason your new, powerful, modern, efficient boiler performs better than your old, low-power, inefficient, clogged 30-year-old one is because its a combi. That's not the reason; it's because it is new, powerful, modern and efficient.

A combi is very suitable for a small home with one person and one bathroom. as you start to increase, they start to get less suitable.

An unvented cylinder (Megaflow is an example) heated by a system or conventional boiler can give unsurpassed hot water, provided the incoming flow from your watermain is adequate.

Combis also need a good water flow.

To measure it, fill a bucket at the kitcher cold tap (also try the utility room and garden taps if you have them), time it, calculate litres per minute delivered.

many houses have quite a small incoming pipe which restricts water flow. It is easier than you think to replace it with a larger one.

My previous homes combi boiler was virtually instant with the hot, my sister's has a terrible lag. My was a Halstead, I don't know hers. So it isn't a risk if you pick the right one (we had similar pipe lengths, both on gas etc).
If you have low water pressure though you might be better with a tank and pump. I know combo's aren't great for this, I'm currently researching my own options and have discovered this, but not well informed enough other than to say definitely do your research before you decide, and to confirm you are asking the right questions.
Take the good advice from here and check it out thoroughly cos if you jump the wrong way you'll have plenty of time to regret it!

Thanks all, really helpful information.

@PigletJohn - tested water pressure at kitchen tap a couple of days back (tap about 5m away from incoming water supply due to kitchen having been moved in the past) by running on full for 6 second, came out at just over 7.3 litres per minutes which google tells me isn't the best.

Replacing incoming pipe would a nightmare (looked into it recently due to leak in the pipe)

Is BG British Gas?
If so I’d be wary
We used them, they overcharged, ruined floorboards today get to pipes and generally was an awful experience
We got finance with them and They also lied saying we could pay off early when we couldn’t - our fault though for not reading small print to be fair but I had given birth the week before and husband was away working
Anyway, just a word of caution

My father has just had a condensing boiler and pressurised water tank fitted.

OMG the shower is so much better!! This is quite an expensive solution but his house was borderline size-wise for a combi and my sister and I have historically moaned a lot about how crap the shower is when we go and stay.

A pressurised tank only works though if you have decent water pressure from the street. I live in a modern flat and have one - but my mains water pressure is poor so the shower isn't great (I appreciate the irony here) and I"m currently investigating things that could make this better when I replace my bathroom.

7.3 litres per minute is not sufficient for a good shower, and when someone turns on a tap elsewhere in the house, flow will reduce still further.

Although it is possible to fit an accumulator tank, the best option is usuall to renew the pipe.

The new one does not have to follow the same route as the old.

It is easier if you only need to dig a trench in the front garden and lift some wooden floors, but there are other ways to do it. Sometimes it can run at the side of the house. Sometimes a mole can burrow underground pulling the pipe behind it (yes, really!)

p.s.

a bath takes around 100 litres.

100 litres divided by 7.3 litres per minute is 13 minutes.

Keep a book in the bathroom.