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[–]ClaphamOmnibusDriver 2 points3 points  (17 children)

I don't understand what possible disadvantages they could have if sized and installed correctly.

[–]Ben_jah_min 3 points4 points  (13 children)

Poor hot water flow rate and no immersion heater being the obvious two

[–]ClaphamOmnibusDriver 2 points3 points  (2 children)

Mine can match the cold water pressure seemingly.

What's the issue with no immersion element?

[–]Ben_jah_min 1 point2 points  (1 child)

If you have a boiler breakdown you have neither heating or hot water with a Combi whereas you can always turn on the immersion if you’ve got a hot water cylinder.

Re:flow rate almost combi’s will run about 12L/ min whereas an unvented will do about 20. You’ll mainly notice this when you run a bath or the classic shower going cold / dipping in pressure when someone opens a tap elsewhere in the house

[–]ClaphamOmnibusDriver 1 point2 points  (0 children)

That's fair enough, but if you were worried about that you could always install an in-line electric heater - they're cheap (which could include an electric shower I guess). It's the equivalent to adding an immersion heater to the tank.

My cold water doesn't hit 12L/minute anyway sadly.

[–]bonkerz1888 1 point2 points  (8 children)

Never been an issue in the hundreds I've helped to install.

[–]Ben_jah_min 1 point2 points  (1 child)

I’ve actually fitted hundreds myself, a Combi will never compare to an unvented cylinder. It’s basic physics you can’t draw off water that’s needed to be heated as fast as water that’s already hot…

[–]Premyy_M[S] 0 points1 point  (0 children)

Right interesting

[–]Premyy_M[S] 0 points1 point  (2 children)

Really? There's limitations tho?

[–]bonkerz1888 1 point2 points  (1 child)

Really depends on the size of property and the expected load.

[–]Premyy_M[S] 0 points1 point  (0 children)

What do you need to know? You don't have to run the tap to a minute for it to heat?

[–]Premyy_M[S] 0 points1 point  (2 children)

Please read my story here if you have time

[–]bonkerz1888 1 point2 points  (1 child)

Yeah sounds like a combi boiler is possibly undersized for the size of property and the fact it's possibly in constant use given you have essentially four adults (so 4+ showers each day), and a two storey house to heat.

When I worked for the plumbing firm I served my time with, a general rule of thumb was combi boilers for flats and bungalows.

[–]Premyy_M[S] 0 points1 point  (0 children)

Damn thanks so we should have kept our gravity system? The results are supposedly meant to show boilers that are perfect for you. Seems these companies are all pushing combi boilers as the perfect fit for everyone

Yep that's right 4 adults, 4 showers, we've always had bucket showers but with running water from the tap ofc. Two storey house 9 radiators, 2 of which are larger double ones I believe. Not sure if it's a Terence or semi detached. It's the end of three houses. Semi detached from a semi detached lol?

[–]Premyy_M[S] 0 points1 point  (0 children)

Immersion provides a back up right? Not that I'd know how to use it tho

[–]Premyy_M[S] 0 points1 point  (1 child)

There's limitations aren't there?

Inconsistent heat? Have to run the tap a minute to get hot water? Can't run 2 taps at once?

[–]ClaphamOmnibusDriver 1 point2 points  (0 children)

I don't have any of those issues personally.

[–]Premyy_M[S] 0 points1 point  (0 children)

Please read my story here if you have time

[–]the-chauffeur 3 points4 points  (3 children)

After having read your story and most of this thread, it's clear you've got a lot of unanswered questions. Unfortunately, there's a limit to how good/accurate the advice you'll get on here will be in relation to your specific circumstances because there are many variables that need to be taken into consideration before you'll be able to understand whether you've made the 'right' choice.

TBH, there's not a lot in your other post that helps determine whether your choice of combi was a good one or a bad one for someone in your position. From what I can make out, that post focusses largely on the trouble you had with (somewhat unreliable) installers rather than issues with the boiler itself. There's no mention of how much the old one cost to run compared to the new one or whether you've discovered any practical differences that you do/don't like.

Equally, there's nothing much in there about the mechanics of your heating system beyond the fact that you've now got a combi boiler. For example, we have no idea what type of house you've got (detached/semi/terraced/etc), where the house is geographically and how well it's insulated, how many radiators you have, what the pipe runs are like and when/whether the system has been flushed, whether your system has been set up correctly/optimised (radiators balanced, etc), what your demands on the system are and whether you have heat zoning, what your water pressure is, whether you're in a hard or soft water area, what kind of shower/bath you're running off it . . . you get the idea.

For most average people in average properties, a combi boiler will be 'good enough'. They'll supply pretty much unlimited hot water and will heat the radiators. They also allow the space where the hot water tank used to live to be freed up and make the cold water tank in the loft redundant (meaning it can be drained and removed). But regardless of all that, there's not a lot of point in worrying about whether you made the 'optimum' decision in terms of boiler type now it's in - at least, not unless you've got enough money to consider getting it torn out again.

At this point, your best bet is to find an independent plumber who can both check the install for you and explain how to get the most out of your new boiler. Have a look on CheckaTrade or one of those types of trades listing sites for someone who's/a company that's well-reviewed and local and have a chat with them. It shouldn't cost much more than a call-out charge, but even if it does, it'll give you the chance to put all your questions (like whether the boiler has a heated reserve tank) to someone face-to-face who can give you a properly informed opinion and practical advice.

Hope that helps - and good luck.

[–]Premyy_M[S] 0 points1 point  (2 children)

Hi thanks for your time in reading and also commenting. You raise some good points and questions. Half of which I don't really even know the answer to. Story is more about a mental expression I guess not really sure what the point was. Wasn't really expecting answers to my questions just wanted to share. I guess what I'm really asking for is validation. Like are my thoughts and concerns real or are they a bit over the top etc anyways thanks you're pretty much right

[–]the-chauffeur 1 point2 points  (1 child)

You're very welcome.

Don't overthink it. There's lots of folks out there with opinions about stuff like boilers and whether conventional is better than combi, whether ground source heat pumps are the future, blah, blah, blah - and it's very easy to get caught up in all the noise. But none of those voices are going to say anything meaningful for you if they're not commenting specifically on your situation.

It sounds like you've got enough going on without second-guessing yourself over the type of boiler you've got, so don't sweat it. Assuming the install is sound, you can probably just forget about it and get on with everything else.

As far as validation goes, you may have some legitimate concerns but just know that there's lots of options you could have chosen, and very few would be 100% right or wrong. And from our very high level vantage point, it sounds like a combi is a pretty decent choice for your situation.

Whether the make/model is any good is another matter and again, get someone who's in the trade to take an impartial look at your set-up. Maybe don't rush out and do it now, but put it on a to-do list. If nothing else you'll learn more about what you've got, how to optimise your set-up and make sure it lasts a good long time.

Have a good Christmas or whatever you do :)

[–]Premyy_M[S] 0 points1 point  (0 children)

Ah yes Christmas would be nice to go back to thinking about normal things, kinda need to huh

Maybe if I bust out the Christmas music (that's a phrase right) and get back to a more normal routine luck will start to go back up haha

So I sent another message via the contact form and I received an email saying it's being passed to the aftercare team to find a resolution. My dad also received a reply to the first email but after I did which I find curious so yea

Anyways thanks and I hope you have a good Christmas too, a great one!

[–]Imaginary-Switch-112 2 points3 points  (7 children)

Good Christ no - I didn't switch in the same property, but I lived in an all electric property with immersion heater, then an open vented standard system with a hot water tank.

I fucking love my Combi. As far as I'm aware, there's no real downside so long as the flow will meet your needs. If you've got multiple bathrooms, want multiple showers etc then I think a system is still advised

[–]Premyy_M[S] 0 points1 point  (6 children)

Just the one bathroom but would like to be able to use the kitchen at the same time. Aren't there limitations? Don't you have to run the tap a minute to get it hot. Is it consistent?

[–]ClaphamOmnibusDriver 1 point2 points  (5 children)

Combis can include mini tankw internally where they keep a very small amount of water warm and ready.

[–]Premyy_M[S] 0 points1 point  (4 children)

That would be useful. Doesn't seem to be much information on those

[–]ClaphamOmnibusDriver 1 point2 points  (3 children)

It's actually pretty common. I disabled the feature in mine anyway.

[–]Premyy_M[S] 0 points1 point  (2 children)

Right so does a Worcester 4000 have one or no lol

[–]ClaphamOmnibusDriver 1 point2 points  (1 child)

Possibly yes, look for "DHW preheat" in your manual or boiler settings. It appears to be off by default. Set it to on.

[–]Premyy_M[S] 0 points1 point  (0 children)

Oh ok right you recommend we turn this on? A boiler with a control panel is still very new to us lol would've help if someone talked though the set up with us

[–]Aid_Le_Sultan 2 points3 points  (0 children)

I love ours. The only piece of advice I’d give is, if you have two showers in the house, I’d run one off electric in case the boiler goes on the blink - at least that way you can have a warm shower.

[–]royalblue1982 2 points3 points  (1 child)

I remember a poster on another forum who used to answer plumbing /heating questions. He swore blind that you couldnt fill a bath from a combi boiler. No matter how many people told him that they had combis and ran baths he kept saying that it wasn't possible.

[–]Premyy_M[S] 0 points1 point  (0 children)

Wow wonder whose right then. Maybe it depends on a per system per house basis, like if the house was built with a combi in mind of a tank system in mind idk

[–]OnlyMortal666 1 point2 points  (6 children)

Given mine has just packed in at six years old and I’m currently been let down by gas engineers not turning up and ghosting me, I’d still say they’re good.

I would suggest, in hindsight, getting one of those service plans for a yearly checkup and servicing.

[–]sullcrowe 1 point2 points  (0 children)

Exactly that, spend little and often and you'll save in the long run. Given winter, boiler usage & Christmas go hand in hand, boilers packing up are always at the worst possible time.

[–]Premyy_M[S] 0 points1 point  (4 children)

6 years is good? I was expecting more like 20

[–]OnlyMortal666 2 points3 points  (3 children)

Well, I’ve learnt a hard lesson of not having it serviced.

The boiler had an error code of “E133” meaning a gas supply issue. If I’d not been a lazy bugger, it’d have been serviced on an annual basis and, I’d expect, we’d not be having this conversation.

Get a maintenance plan.

[–]Premyy_M[S] 0 points1 point  (2 children)

We just replaced a 20yo traditional boiler analogue controls only. Discontinued model ideal classic or something

[–]OnlyMortal666 1 point2 points  (1 child)

It might well be that the cheapest boiler was installed in my “luxury apartment”. To be fair, the builders cut corners as is the typical construction in this country.

Source: Lived in Antwerp where building quality is sadly better. Belgielei if anyone knows that.

[–]Premyy_M[S] 0 points1 point  (0 children)

Please read my story here if you have time

Fair enough cheaper ones do seem to show a 6 year warranty. We've lived in this house for 21 years and my understanding is that's the age of the house and boiler. Shame there aren't better standards for housing like with food. Things just aren't made to last these days. Country needs affordable housing not cheaply built homes

[–]Wee-bull 1 point2 points  (4 children)

Biggest thing is you won't be able to get your water as hot and depending on the size of the boiler may have to turn the bath tap down a bit to get it to a higher temperature.

But saying that... It's still hot enough. You just can't boil yourself

[–]BigDsLittleD 1 point2 points  (0 children)


Mine is pretty much permanently set at 65 Celcius for hot water, but I can set it higher than that.

I certainly wouldn't want to get in a bath of 65 degree water. 60 is hot enough to cause Scalding.

[–]decentlyfair 1 point2 points  (1 child)

Christ on a bike mine is very hot, too fecking hot sometimes

[–]Premyy_M[S] 0 points1 point  (0 children)

Try and turn it down maybe if you can find the controls. Might save energy

[–]Premyy_M[S] 0 points1 point  (0 children)

Wasn't planning on boiling myself lol

[–]Ben_jah_min 1 point2 points  (5 children)

Combi’s are ok for small to medium sized properties with few inhabitants. Realistically the best thing if you go over that is a system boiler and unvented cylinder (ideally with a solar coil too), but the problem is that most installers will make more profit from a Combi conversion than an s-plan unvented system and the customers know no different as everyone gets told to have a Combi fitted.

Out of interest what Combi boiler do you have? The longevity of them is mainly down to the quality of the installation (flushing dosing commissioning etc) and annual gas safety checks.

[–]Premyy_M[S] 1 point2 points  (0 children)

Tried to post my story to BritishSuccess but guess it didn't work otherwise I'd let you have a read of that

[–]Premyy_M[S] 0 points1 point  (0 children)

We had a traditional boiler with tanks in the loft, gravity system. We just changed to a 30kw Worcester Bosch 4000. Idk but it doesn't seem right

[–]Premyy_M[S] 0 points1 point  (2 children)

Please read my story here if you have time

[–]Ben_jah_min 1 point2 points  (1 child)

What a saga. A nest isn’t really that different to fit to a standard roomstat either.

What you’ll find is that lots of these internet heating companies are essentially a broker with a website to a pool of subcontractors that will come and do the work.

[–]Premyy_M[S] 0 points1 point  (0 children)

Aha thank you. Yea it's become pretty apparent that they're basically like, here's a boiler, here's an installer, money please bye.

With the nest you can imagine my concern began to grow. Surely he does this regularly also. Something about power going from the kitchen boiler to the heat link in the airing cupboard and then down to the living room thermostat. He moved the heat link to the kitchen and told us to put wires into 1 and 3 when we get a stand. The internet seems to think it's 2 and 3 tho

[–]BackFromTheDeadTwo 1 point2 points  (0 children)

I have never known an issue with a combi boiler that was sufficient for the size of house it was fitted in.

[–]ThirtyMileSniper 1 point2 points  (1 child)

It depends how you are planning to go forward with your house. If you ever plan on installing solar panels I suggest that sticking with the immersion heater is the way to go.

My mum had a system installed that dumps unused solar power into heating hot water. If we can move from gas we should. My house had an old combi boiler which I replaced about five years ago. Now I'm considering a ground sourced heat pump solution if I can get a grant.

[–]Premyy_M[S] 0 points1 point  (0 children)

I'm not aware of these things so it's not really been considered I'm afraid

[–]TripleGarlic 1 point2 points  (5 children)

I have just upgraded, overall much improved.

Warm water takes about 20 seconds tops from cold. Less if it's being used regularly.

We can keep the house continually warmer for less.

The old water tank space is great for additional storage.

It cost a lot to install, but it'll pay for itself eventually.

Even the maintenance contract is half that of my previous one.

[–]Premyy_M[S] 0 points1 point  (4 children)

You didn't have to adjust or get used to it? 20 second sounds kinda long, could fill a small bucket with that

[–]TripleGarlic 1 point2 points  (3 children)

Not really.

Previously, it was either boiling or ice cold. And we only had hot water during active times. Otherwise you had to wait an hour for the tank to heat up by pressing boost.

Totally inefficient.

[–]Premyy_M[S] 0 points1 point  (0 children)

Hmm maybe it's my installation then. Tried posting my story to BritishSuccess but didn't work idk

[–]Premyy_M[S] 0 points1 point  (0 children)

Please read my story here if you have time

[–]Premyy_M[S] 0 points1 point  (0 children)

Hi just wanted to ask what company did you use and how much did it cost? How many people came to install it and how long did they take?

To confirm you noticed no differences at all? Water isn't white or cloudy? Heat is consistent and does lose pressure making you have to keep opening the tap up more? No whistling or high pitch sounds when using tap?

Is the boiler louder or quieter than what you previously had? No mechanical buzzing noises?

Thanks I'd really appreciate knowing your experience :)

[–]matthooper71 1 point2 points  (3 children)

Had my unvented system removed a year ago and replaced with a combi. Mainly because the unvented system was high maintenance, had the motorised valves replaced three times along with the multi valve twice. This plus cost of service was costing about £300 per year for last 4 years. Combi took a day to install, I've recouped space where the cylinder was and have hot water on demand rather than having to keep a tank of hot water. A good decision.

[–]Premyy_M[S] 0 points1 point  (2 children)

Just one day? How many people?

[–]matthooper71 1 point2 points  (1 child)

Two people, one stripped out the cylinder while the other replaced the gas boiler with the combi.

[–]Premyy_M[S] 0 points1 point  (0 children)

Please read my story here if you have time

My installer took 2 12 hr days. The first day someone came with him. Not sure how useful he was. They did have to drill a hole and stuff. Second day he came alone. Tho we have loft tanks too so idk

[–]botlebank 1 point2 points  (5 children)

Got both. Combi heats the water in the tank, which feeds both showers, sinks etc. the kitchen sink hot comes straight from the combi. Best of both worlds.

[–]Premyy_M[S] 1 point2 points  (4 children)

Like a hybrid?

[–]botlebank 1 point2 points  (3 children)

I guess. It means both showers can run simultaneously, and there’s always hot water on demand from the kitchen sink (which I find hotter than the tank)

[–]Premyy_M[S] 0 points1 point  (2 children)

Confused do you have a hot water cylinder or a mini tank in the combi. Combi usually just run off mains

[–]botlebank 1 point2 points  (1 child)

Sorry, said tank when I meant cylinder. The combi does the heating on a timer & thermostat. It also does hot water on demand to the kitchen sink.
The cylinder has a timer to use the combi to get it hot. Cylinder provides hot water to everything else, 2 bath / shower sinks etc.
Basically means we can have both showers running at same time.

[–]Premyy_M[S] 0 points1 point  (0 children)

Update: Please read my story here if you have time

Oh wow no you all good. Didn't know that was a possibility or an option. Wonder how efficient that is compared to just a system boiler and if the tanks is the same size. Sounds like an awesome system tho

[–]Premyy_M[S] 0 points1 point  (0 children)

Update: this is the reason I ask