Boiler help!

[morethanmama]

We are planning a refurb and extension to our largish house. Our boiler needs replacing and plumber has recommended a high output combi Worcester Bosch 42 from memory.

I have read about something called megaflo and think that might be what we want in time as we have 3 children plus both of us and various guests from time to time so will have a lot of simultaneous demands for hot water. We are going to want underfloor Heating downstairs and will have three showers.

Are they really expensive? Do you need loads of room for them ? Can anything go in the loft ?what Are the die sides?

Sorry fir lengthy post....

A megaflo isn't much bigger than a standard hot tank - same footprint, just a bit taller. It can go in the loft, the garage, the airing cupboard - wherever makes sense and you have space.

You get rid of a lot of inside pipes (and the cold tank) with most installations, so there is less risk of flood or frost damage.

You also don't need pumps for showers because they provide pressurised water, so if you have lousy water pressure they are great.

As far as I can tell from our bills, a megaflo isn't more expensive. Probably less so because it delivers "instant" hot water more efficiently than a hot tank sitting around bubbling for hours on end.

No downsides that I know of.

Worcester Bosch boiler is what we have. Apparently the best of the best, and no trouble with it after 5 years.

the key to having good results from a Megaflo or similar, is the amount of water (litres per minute) that the incoming water main delivers to your house. Fill a bucket at the cold tap in the kitchen, and at the utility room tap and the garden tap if you have them, time it to full, calculate how many litres per minute you get, see which is the best. some taps restrict flow.

Once you do away with a cold water tank in the loft, the amount of water that comes out of all the taps in the house at any one time will not exceed the amount delivered by the incoming pipe. Modern houses often have large 25mm or 32mm blue plastic pipes all the way to the pavement to get a good flow. If you have a dented, twisted half-inch lead pipe you will not get much.

Running a new pipe is easy or difficult depending on what you have to dig up to lay it.

they provide pressurised water

Only to the extent that the incoming water from the main is pressurised. So if you have low pressure, you will get low pressure.

I thought I might bring pigletjohn out of the woodwork if I replied.

Yes, you might need a new incoming pipe - we did, but it wasn't too big a job or too expensive.

We def need our main replaced. Think we are still on the lead. What about the avaliability of hit water - I love a combi for that.

Should I expect to pay more than for a new (top spec) combi ?

Thanks v much.

When you have a new water pipe, that delivers (say) 20 litres per minute, then you can get 20 litres per minute of fully-hot water from a Megaflo.

If your pipe delivers 30 (or 100) litres per minute, then that's what you can get from your Megaflo, subject to the size of your pipes and taps. Hence it is an advantage to have a good big one (often 150 litres or even 220, so it can fill two baths at the same time). By the time the first person gets out of the bath, it will be full of hot water again (typically 20 minutes with a modern boiler and good pipes). The temperature of the hot water will not change if someone else in the house turns on a hot or cold tap.

A combi can only deliver a limited amount of hot water (typically 12 to 15lpm) and the faster the water comes out, the less hot it is. If someone in the house turns on another tap, the temperature changes.

Guess which I prefer?

If for some reason you want to, you can have a combi boiler feeding, say, a downstairs shower, and also heating a cylinder or megaflo for the upstairs bathrooms. Apart from a very few young and inexperienced ones, any plumber knows how to do it.

What is involved in removing the lead pipe? What was the rough cost and timescale? Who does it, plumber?

it involves digging a 500mm deep trench to lay the new pipe in. You might have to get the water co to connect it to the meter or pavement watermain. If the old lead pipe follows the same route you can dig it out and sell it for scrap.

The water co will inspect your new pipe and trench to see that it has beeen properly done before you are allowed to fil it in.

If you have a lead pipe, ask then them at once to come and test your drinking weater for lead content, because they may have a lead-pipe replacement subsidy, and may connect your new pipe free. Last time, they were so slow coming that i had replaced the pipe before the tester came, so I got no subsidy.

Digging trenches is hard work and a plumber may prefer that you, or labourer, does it. I think I paid £200 to trench a gravel drive. It is harder if you have a concrete floor and drive. You can get molers to do it at extra cost.

Our new pipe was done with a mole. Unbelievably noisy and it felt like the house was going to fall down, but it was really quick.

Thanks for the information.

Pigletjohn, why might I want a combi feeding the megalflo. I'm not sure I understand why I would want that? Thanks

I have come across it, very unusual, can't quite remember why. Might have been a house where they wanted multiple long showers one after the other, which a combi can do as it never runs out. Perhaps they had teenage daughters.

However a megaflo or similar can hold one or two hot bathfuls of water, and can deliver it faster and hotter than a combi, so I would say is generally preferable in a house which has several people, and a bath, or more than one bathroom. I find combis very annoying when two people are running taps at the same time.

We have a combi boiler and while it is brilliant for instant hot water you can't pressurise the system. You are reliant on the mains water pressure which can be disappointing. I also worry about having no cold tank in case of zombie apocalypse

I live in a small town, and five years ago or so we had a major burst which cut off the supply for a day and a half.

I have a big cold tank, enough to carry on washing and cooking as normal for longer than that (but no baths)

my unfortunate neighbour told me he used the water from his kettle to shave and brush his teeth. If I'd realised i would have invited him in for a shower.

AFAIK it is very rare for water to be off for more than an hour or so in a town. No zombies round here.

Hope so! There were big problems with water here a few years ago - lots of burst pipes, no water at all for several days. If it happens again we would be screwed.