Combi Boiler vs Hot water Cylinder

[Andeh13]

I have put up with having a warm air system for almost 2 months now, and it is rubbish! it warms up very quickly, but the house cools down at an alarming rate (though a lot of that will be put down to poor insulation). What really bugs me is that my room is quite far from the system & by the time the air gets to my room, it is cool...not nice when you are up 6.45 on a frosty morning!

I am now ready to put money down on a new setup. My choice is between a combi boiler and a typical hot water cylinder setup.

I am in a mid sized (ie 3 double rooms) semi-detached house, with a large open plan lounge/dining room and down stairs spare room, 7 rads & a towel rail. I don't use much hot water at all, but for future resell value someone else might. I don't use the heating much either (I can see my breath atm, and am feeling quite toasty with a jumper on) but again future occupants might. I do have a bath but don't use it much, I also like quite a powerful shower (who doesnt?). I also have very poor water pressure, something around 10L/min and every quote I have had so far recommends the smallest combi boiler they do.

The latest guy who came out (he has an awsome repuation) advised against a combi boiler, saying they were designed for flat originally and with such a low water pressure I would be better off with a cylinder system. The others (random companies I have found online) are quite happy to advise a combi boiler, but mainly because I suggested that to start off with.

The issue is I don't know which to go for. The hot water tank etc is more expensive but I am not too fussed with this, it is the running costs I am more concerned about. I know a hot water cylinder will be more to run...but no one can give me a definite figure to work out if it is worth it or not.

On the off chance someone on here knows their stuff with heating systems...can anyone offer any suggestions?

Cheers guys

[GoNz0]

did you ever find the stopcock to see if it can be opened up more ?

i would go combi, ours has a mini hot water tank and i can decide when it is pre heating due to buying an upgraded wireless controler.

beats heating up a tank of water you "may" use

every penny counts!

[Zak33]

A) Open your kettle
B) look in it
C) judge if it looks like a shiny new pin after many months of boiling water or like a chalky hell hole.

If it's clean, you're in soft water area, get a Combi
If it's like a chalky powdery hole, get a boiler and a hot water tank

You see, the water in the loop of copper pipe, that goes into the boiler and then into the tank to jheat the take, is the same water.. it stays in a loop all bar any minor leaks, which are refilled by header tank. The hot PIPE heats the water.... the water itself conducts heat via the pipe coil in the tank.

A Combi boils the water as you use it....and in a chalky area, it builds up DEAD FAST and it gets ruined.

[0iD]

A) Open your kettle
B) look in it
C) judge if it looks like a shiny new pin after many months of boiling water or like a chalky hell hole.

If it's clean, you're in soft water area, get a Combi
If it's like a chalky powdery hole, get a boiler and a hot water tank

Not necessarily so, there are some great in-line anti-scaling devices available these days, just get a combi.

Here's one I've just put in my loftspace.


Groovy wi-fi portable controller & room-stat.


The only downside is I had to ditch the power shower as it drew too much pressure from the system, but the system has enough pressure to cope with a conventional one.

Your mains pressure will be the deciding factor imo.

[Andeh13]

Yup, stopcock is as open as it gets! . Bugger, 10L/min is a pathetic amount! Am really umming & arring. Its the shower pressure that is my main concern, but tbh I have a terrible shower as is & make do with it, anything thats a step up from it (its 8.5kw) would be a benefit! I have a new kettle so no idea about soft/hard water, I am int eh shower East near Gatwick? From google I think it is a hard water area!

With me spending most weekends out of the house & using very little hot water (got a dish washer etc) I suppose heating up a big cylinder of water for minimal use wouldn't be much good!

[peterb]

I thought we had a time warp here!

http://forums.hexus.net/general-disc...te-advice.html

http://forums.hexus.net/general-disc...l-heating.html

A lot depends on the number of occupants - a combi is limited in the amount of hot water it can produce - even a multi-point, but the plumbing infrastructure is less (no hot water tank for a start)

The point about the hardness of the water is important, but a reputable installer will advise on suitable water treatment - ranging from an ion exchange unit that softens the water to something that adds a small amount of a chemical amount of a chemical to stop limescale sticking to the pipework.

I think it was covered in one of the threads I have sign posted above, as was some general heating advice.

http://www.gasboilerguide.co.uk/

[Andeh13]

I thought we had a time warp here!

http://forums.hexus.net/general-disc...te-advice.html

http://forums.hexus.net/general-disc...l-heating.html

A lot depends on the number of occupants - a combi is limited in the amount of hot water it can produce - even a multi-point, but the plumbing infrastructure is less (no hot water tank for a start)

The point about the hardness of the water is important, but a reputable installer will advise on suitable water treatment - ranging from an ion exchange unit that softens the water to something that adds a small amount of a chemical amount of a chemical to stop limescale sticking to the pipework.

I think it was covered in one of the threads I have sign posted above, as was some general heating advice.

http://www.gasboilerguide.co.uk/

You know what, i totally forgot about the previous thread. I remember asing about warm air vs conventional but totally forgot that I'd asked this question before! . Sorry about that!

Back then I thought I could put up with the warm air system for a bit longer, but enough is enough no point putting it off for the sake of putting it off! Will have another read of those threads & see if I missed anything off. Thanks for the link

[Zak33]

I stand by my Hard Water/Soft Water decider here.....

If your water is hard... get a hot water tank. And change it after about 10-15 years.

[Andeh13]

I stand by my Hard Water/Soft Water decider here.....

If your water is hard... get a hot water tank. And change it after about 10-15 years.

The Combi boiler comes with a 5 year warranty, would that make any difference to your advice?

edit: now that I mention it, I wonder if a warranty would exclude something along those lines (hard/soft water build up!)

[[GSV]Trig]

Theres always the option of getting a water softener, not only will it help with the heating but everything in the house you do that uses water will benefit..

http://www.qualitywater.co.uk/

[Tumble]

If you have radiators.... are you SURE it's a warm-air heating system? or is it some kind of hybrid setup?

[CaptainCrash]

The issue is I don't know which to go for. The hot water tank etc is more expensive but I am not too fussed with this, it is the running costs I am more concerned about. I know a hot water cylinder will be more to run...but no one can give me a definite figure to work out if it is worth it or not.

A cylinder system needn't cost significantly more to run - if you think about it, it takes "x" amount of kilowatt-hours to raise "y" volume of water by "z" degrees, whether it's heated instantaneously(ish) by a combi boiler or by a heat exchanger in a cylinder. You don't reheat the entire cylinder every time you use hot water, only the amount of incoming cold water that replaces what you've drawn off - there will be some efficiency loss from heat radiated through the walls of the cylinder, and the heat exchanger flow and return pipes, but this should be minimal with decent insulation (and in winter, even this small loss isn't "wasted" as it will contribute to heating the house).

Also, if a combi boiler goes wrong, you're left without hot water as well as space heating, whereas a cylinder will usually have a backup immersion heater - it might not happen very often, but it can be a major pain in the proverbial when it does, particularly if there's several people in your household (and take it from someone who knows, it will inevitably be at Christmas/New Year during the coldest winter for thirty years or more).

I'm not a great fan of combi boilers, IMHO their main advantage is cheapness/ease of installation when you're installing a system from scratch. I think in any case, if you have very poor water pressure the decision is more or less made for you - even if a combi boiler will actually work, it's likely to be a pretty unenjoyable experience...

[peterb]

Captain Crash makes a good point, and I think in the other threads you said you liked a good high pressure/flow rate shower. A hot water tank is certainly the way to go if you are thinking about a shower pump.

But make sure the tank is of sufficient capacity - a power shower can use a lot of hot water very quickly.

[zigojacko]

Combi boiler every time, who wants a hot water cylinder these days. Instant hot water and heating at the same time if required, yes please, especially through the winter months.

[oolon]

If you use a themal store, you can then get hot water at mains water temperature. The store can also be heated up solar. Boilers work best when the can run for a while, the energy (heat) drawn from the store will no instantly be replaced, only when it drops under a threshold (then it will charge for a while), use of mixing makes the water temperature constant so you don't get a drop in temperature when some hot water is drawn, in a normal cylinder this would be replaced with cold, reducing the hot temperature. With a microCHP this would get the best use out of a generation system.

[GoNz0]

is the 10lt a min at the shower or all the taps in the house ?