O/T - Domestic Hot Water Question

[RichP]

Morning all

I'd appreciate anyone's feedback on the merits of:

(a) standard condensing boiler with mains pressure (megaflow?) hot water tank

(b) combi boiler

We currently have a standard condensing boiler in the loft with a normal low pressure tank on the landing, but I want to move the hot tank into the loft as we to use the space for something else. The current tank (I think) won't work in the loft as there'll be no decent water head to fill it from. So, we need to change either to a high pressure tank or a combi boiler.

Personally I hate combi boilers as in my experience you seem to wait for ever for hot water to come through, then as soon as you turn a hot tap off an back on again you get a shot of cold water as the boiler shuts down and then restarts. However SWMBO's keen on combi as you get a never-ending supply of hot water for the shower, and I can see this merit.

I like the idea of the high pressure hot tank as you get a good shower pressure but none of the boiler shutting down / starting up issues as with the combi.

Amount of water used is of no bother to us as we're not on a meter anyway. House is currently a 3 bed, but will expand to 4 at some point so the solution needs to copy with a potential "increased population"!

Ultimately we need the best cost least hassle solution, so I'd be interested in peoples thoughts either way.

Many thanks

Rich

[Man On The Clapham Omnibus]

I wouldn't feel qualified to advise, but I do want to put in a vote against combis. 'Virtual' hot water in my experience - okay for a flat but not for a family house.

[V8grunt]

I personally would go combi.

I've had one in the last 2 houses, first house I used a pump for the shower, like standing under a waterfall, hot water on request,

The one in  our new place I had moved in to the loft to get extra space, hot water on request and no problem with hot/cold situation you describe.

[nik9669]

Combi's are better now than before, but if you have a 4-bed house, how many baths/showers are likely to be used simultaneously? If it's too many, the combi may not cope adequately. Megaflow may be a hot water storage solution rather than a heat-on-demand, but it's a mains-water-pressured output so will serve multiple showers etc without the need for pumps. Make sure, if you go that route, the installer is correctly qualified and registered to work on Unvented water systems. If in doubt, ask to see his card to prove he's ok to install it.

[CedricTheBrave]

The system in my house is brilliant, I have no idea what its called but it uses a standard small boiler in the garage and the hot water tank is kept hot by that all day. the radiators get hot instantly they switch on which is great when you walk into a cold house and the hot water is run off heat exchangers within the tank. all of these are fed with pumps so you get great showers. The tank is fully enclosed and insulated as well.

[smegablade]

Rich,

we have a megaflow system in our four bed and as far as I'm concerned it's the best system I've ever had, seen or used.

Gives us the same pressure as a power shower in all three showers and the tank is large enough to give us all the hot water we ever require.

I think you're fairly local to me, you're welcome to come over and have a look. PM me if you'd like to

Ian

[Martin Keene]

A combi won't cope with a 4 bed house. Fine in a flat with one bathroom, 4 beds and two bathrooms, no.

[Mat Jackson]

A combi won't cope with a 4 bed house. Fine in a flat with one bathroom, 4 beds and two bathrooms, no.

Sorry - it will.....

I have a 4 bed house and the combi is great.

Just buy the biggest powered one you can.  The problem is people often size them for the heating requierments of the house and they then cope with the water flow.  For that reason we went for the biggest available to ensure maximum water flow and it is great.

BTW, the biggest one wont use any more gas.  It is the energy efficieny of the house that dictates that.  the bigger boiler will simply run less than a smaller one.

[chazpowerslide]

We have a Combie in our 3 bed semi and it's been fine, we got the biggest capacity one we could ans it runs 8 rads and all the hw requirements we need for a family of four.

It's ecanomical too.

Chaz.

[stantman]

NHBC went through a stage of not allowing a house with 2 showers to be fed by a combi as they couldn't cope with peak demand.

Combi boiler capacities have increased since then and cope better.

Which ever you get as its condensing make sure you can get to the over flow style condensing pipe. This allows water from the boiler to drip away. Last winter 80% of problems with condensing boilers were because these drips had frozen in the pipe causing it to block and back presure to build up. A hair drier cured the problem (if you can reach the pipe).

Finally and anecdotally have heard combi boilers break down more often due to the instant heat requirements putting large demand on the boiler.

I am only a QS so check this with a plumber.

[Captain Colonial]

Finally and anecdotally have heard combi boilers break down more often due to the instant heat requirements putting large demand on the boiler.

Heard the same from a gas engineer friend of mine.  Got an 20-year old Potterton condensing boiler and he told me to hold on to it until it died, and when it did not to get a combi in his humble opinion, but that he was grateful for them and the steady income they provided!

Plus the changeover payback period for me based on our circumstances and projected inflation and fuel costs would be 17 years - and I won't be in this house another 17 years, thanks.

As always, your mileage may vary, your house is at risk if you set (fire to it, etc. - see disclaimer below.)

[Darrell O'Neill]

Last house I had was a 5bed house with a combi. Infact the last three houses Ive built have had combi's

The only issue I had was you had to use abit of water to get the hot to come through in the en-suite, but then again the boiler was probably 18-25 mtrs away from that point. IMHO it depends how far away the boiler will be from the main point of use.

I still reckon the amount of water wasted over a priod of time was still less than the additional cost of the megaflow, boiler set-up.

Id go combi everytime

[highwayman]

Do they have running water in Cornwall?  

Have a viessmann 32KW combi  and it is excellent for providing hot water at several places at the same time and as most combis has a small store of hot water in the boiler all the time. Dont hear the germans complaining just the brits!!

[fatbaldbloke]

We have a condensing combi in the loft.  4 bed house.  I guess it gets a bit marginal if we have 2 showers running together, but we've gained all the space that the old boiler and the hot water tank took up, plus a healthy rebate from the gas company.

[Bob Green]

A combi won't cope with a 4 bed house. Fine in a flat with one bathroom, 4 beds and two bathrooms, no.

Disagree.