Combi boiler vs water tank

Pelepeg

Hi all.
New to this forum - I've had a search and can't see a similar thread. Apologies if I've missed one and can you please point me to it.

Two years ago we moved from a flat with a Combi boiler to a house with a boiler/water tank set-up. The flat had issues with the hot water to the shower (a mm difference in the tap meant scalding or ok temp water) but I don't know if this was to do with the shower or the water system. Anyway, we need to replace our boiler in our house and so have had quotes for a Combi. All good so far. Then British Gas came to quote and told us we didn't have a strong enough flow for a Combi to work properly, and then it would be costly to get a new tank when we wanted to change back. This engineer seemed suprised that nobody had checked the flow before. I've asked a couple of neighbours - all have combi's with no problem - including the plumber who lives opposite. And then to add to the mix, I had someone around to talk about solar panels, and he said if we do change to a Combi, to keep, then tank as we can use solar panels to heat our water (using the tank to store said hot water).

So, my questions are: Do we take notice of the BG engineer? Pros and cons of Combi over tank?

Thanks for getting this far. Answers all appreciated.

Cardew

The advantages/disadvantages of a combi or system boiler are discussed time and again on MSE, without any conclusions being reached; it is a matter of personal choice.

Without question the big disadvantage of a Combi is the limited output of hot water- particularly in winter when the mains water temperature is low - against water from a HW tank.

Much also depends on the siting of either boiler and thus the length of pipes. Several people have complained about the length of time it takes for hot water to come from a Combi

A combi saves space by eliminating two water tanks.

I currently have both - the combi in an annex - and would never get a combi for the main house. IMO a HW tank is much the better system.

P.S.
Re having 'someone round to discuss solar' be careful - you are swimming in shark filled waters!

In the Green and Ethical section of MSE there are lots of experts on solar, and you would do well to discuss any prospective solar system before committing yourself.

Cardew

If you do a 'forum search' putting in 'Combi advantages' you will find pages of threads. see:


http://forums.moneysavingexpert.com/search.php?searchid=158897277

amtrakuk

Dependent on your fuel type you can go for gas or electric. I use electric for hot water. I wouldn't recommend on demand electric as they just don;t heat the water enough. Electric tanks - I would recommend a Thermal store as it provides mains pressure hot water but without the need for pressure relief valves or annual safety checks as un-vented cylinders should have carried out.

Seronera

If you have the space for a cylinder always go with a cylinder in preference to a combi. Its like driving a BMW instead of a Ford Fiesta.

You also keep your hot water in the event of a boiler breakdown as long as you have a backup immersion heater. If you go for an unvented fast recovery cylinder on a pressurised system you need no tanks in the roof space either and you get mains pressure hot water. All the advantages of a combi and none of the disadvantages.

I install and repair both, I have also owned both (and still do). I know which one heating engineers prefer and which one the 'chuck it in' merchants prefer. I'l let you guess which. I also know which breaks down the most as well.

However right or wrong the BG man is about flow rates, BG will be expensive, and a reputable local company will do just as good a job for much less, and be more available for backup and will not flog you stuff you don't want or need.

This is MSE after all. I'm shocked at the prices some people pay BG for perfectly adequate, but very ordinary installations.

Robwiz

The issue with the shower could be evidence of the low flow rate. But it sounds like a problem with the mixer valve in the shower.

I wouldn't have a combi – it takes a much more powerful boiler to produce enough hot water on demand. But I wouldn't use a gas boiler to heat water either – Economy 7 electricity is more efficient and works out cheaper.

st999

But I wouldn't use a gas boiler to heat water either – Economy 7 electricity is more efficient and works out cheaper.

How much electricity do you use in a day to heat your water?

Robwiz

st999 wrote: »

How much electricity do you use in a day to heat your water?

We have a 1 kW element so that it can be used when we are generating surplus solar PV.

The immersion heater is timed to power up overnight. Last night it was on for 4 hrs 15 minutes before reaching the set temperature so it used 4.25 kWh. We only use hot water for showering – our washing machine and dishwasher are cold fill.

cbrpaul

I have a combi fitted, 3 local installers all quoted, 2 of the quotes for the boiler was under sized ( after much research) , the 3rd quote quoted a higher KW boiler.


This installer even said your HW flow rate will be much better and that many combi installs are under rated, giving the impression that combi,s are not very good with HW flow rates !!


I do know my shower is far better than when we had a HW storage tank fitted !!


My vote goes for a Combi ever time

GwylimT

My current flat has a combi and my last two houses did, I find it to be a far better system, when we had our boiler changed from a standard to a combi our gas bills were quite a bit lower, plus we made a bit of money from selling our two water tanks.

When we had a water tank it was fairly large, but you could still only get two baths from it, or three showers so we had to have an electric shower so we could all wash in the morning.

st999

4.25 kWh

So how much do you pay for a kWh?