Megaflo installation

[HollyMaingate]

Hi all,

I'm looking to upgrade my system from a traditional vented system to an unvented, the main reason being we're having a loft conversion done and the current setup is inadequate, plus the tanks need to go from the existing loft space. I've had a quote from a company recommended by the loft company and wondering if it seems reasonable?

The current main is lead so needs to be replaced with MDPE as our flow isn't good enough, the provider will do their bit to the boundary but there's then approximately a 20 m run to the existing stop cock, underneath the side path so a lot of labour in digging that out and then making good.

I am also having all the pipework moved from its current location in an airing cupboard to the other side of the same internal wall in the 2nd bedroom and will build a wardrobe round it at a later date, the reason being the current airing cupboard space can be better used to either make the existing bathroom bigger or make the bathroom smaller and have a study/single bedroom in the future.

Sorry for all the rambling - any comments or advice would be much appreciated, many thanks!

Water main
-Excavate trench to run alongside of house from outside stopcock position to new inside stopcock position adjacent to fridge.
-Run new 25mm blue plastic mains water pipe work and connect both ends.
-Backfill trench and make good.

Megaflo
-Remove existing cold water storage tanks, F & E tank hot water cylinder and associated pipe work.
-Supply & fit new 250 litre Megaflo indirect hot water cylinder including pipe work, fittings and valves.
-Supply and fit new 12 litre expansion vessel & pressurization kit (for central heating).
-Adapt electrics for new Megaflo.
-All the above to be fitted in back bedroom. (cupboards to be fitted by others).

Total £5000+VAT

Forgot to add I'm in SW London

bump

I did almost exactly that last week so good timing.

Water company - they will come around to install/upgrade the supply pipe once I had mine done but it turned out it wasn't lead and has good flow.

Pipe run from meter to your house - I don't want to lift up all the floor at ground floor so I found this moling firm impactu who can dig just two pits and run their drive to create a new pipe around the side of house then put a new connection inside your house. This connection doesn't has to be installed at the old stopclock position. This should be cheaper than digging 20m trench. There are other similar companies but they give me the cheapest quote. Besides, it only took them 1/2 day to complete 8m + install new connection.

Lead pipe, are you sure your internal pipes ain't lead? Ripping out floorboards and walls to replace them will cost quite a bit.

6k all in sounds a bit steep but I guess 20m dig will cost a fortunate. The 250L cylinder costs around 550 (not megaflow branch) but I didn't care. Def suggest you to compare moling quote and your builder's digging effort.

Thanks for this. I've been looking in to moling companies and first quote for that has been 900+VAT. May I ask what you paid to have that part of it done?

I'm definitely lead from the road to the stopcock (in the kitchen) after which it's copper for the rest of the house. Good point about it not needing to go to the same route it does currently, I'm sure I could find a shorter/cheaper run.

Thanks again

I paid 660 all in (cash discount :-)

My builder told me he would have to charge a lot more if he has to dig the trench.

Doesn't sound completely unreasonable.

A pressurised cylinder which isn't a branded Megaflo will be about £700 for a 250l but a 250l megaflo will be about £1100.

So if you're being quoted £5k for a branded Megaflo plus installation and a new water main that doesn't sound unreasonable.

Fyi. Not all water companies replace your lead main for free.

As you're in SW London, you're with Thames Water. They don't replace lead main for free.
They replace it up to your property boundary. So once you're off the street and onto your front drive/garden, then you'll have to pay.

Best to check that your existing plumbing can withstand the extra pressure. A few months after we had our Megaflo installed, we had a leak under the ground floor, where joints in embedded pipework had failed.

be sure to ask your water co to test your drinking water for lead content before you start work. Afterwards is too late. They may take quite a while to schedule the test.

We used moleing company as we had 40m+ run of drive to replace. Our guy did it for £500 (but he was very cheap & we're in NE)
Ours cost £6500 all in but included a new WB boiler, power flush to system , 30 new TRVs, room stat & controls and magnaclean. But again we're in NE & we went for a different brand from mega flow but still with good guarantee
Haven't regretted it for a second & as we also replaced all our bathrooms & kitchen we didn't have to worry about the fittings not being suitable for the pressure

I don't think it has to be a specialist moleng company - some plumbers etc do it anyway -(perhaps they subcontract that bit of the work - might get a better rate).
A neighbour had their lead pipe replaced quite recently - iirc they could get a grant to help towards the cost? might be worth looking into.
And in the end the (local) plumber they used dug a trench but it was still cheaper than the quotes with a mole (but it was a relatively short run).

And another one saying have all your pipework checked - and things like showers/taps.
When I had CH installed in this house it went from a vented tank to a mains pressure combi. They put 'do not use tape' on my shower - the guy who did the quote thought it was an electric one - thankfully they managed to work around that. The shower head on our bath (not used as a shower) is dodgy as hell - temperature fluctuates hot to freezing.
But the worse was the increased pressure blew the plastic hot water pipes off at the joins (they were one of the early type plastic pipes, hard to get new inserts/fittings and had been installed by a DIYer I call Mr. Bodge-it so not fixed to anything and run in such a way you couldn't fix them to anything) not just leaks - after a couple of hours the pipes started flying off -literally waving around in the eaves cupboard - water everywhere, like turning a high pressure hose on! And we fixed one join and then another went...
Result was the hot water had to be turned off for a couple of days and it cost me an extra £400 or so to have the pipework replaced with copper....

So get it checked and/or make sure there isn't an exclusion clause in the paperwork...
(But do get a tank ...I now hate combi boilers. Water from a large capacity tank is much better - although be aware with unvented if the mains water goes off you can't access the water in the tank - unlike a vented tank where you can until its empty)

Hi, some really good points raised here, thank you all.

MrsFlorrick/PigletJohn - correct I'm with Thames Water and again that they will only replace to the boundary. I sent off for the lead water test kit last week which they said should be with me within 10 days. I then need to take a sample and send it back to them. Looking at some old forum posts Thames did a subsidised replacement on the homeowner's side while they were doing their bit too - have you heard of this?

Wonkylegs - sounds like an absolute bargain - wish I could find those sort of prices down here!

80sMum/Unlucky83 - very good point about the existing plumbing and the pressure. I've just laid a new oak floor and had to move the radiator and extend the pipes so used JG Speedfit fittings on to the old copper, extended with plastic then connected that to the old tails - I wouldn't fancy having to rip up a new floor. That said many new houses are plumbed in plastic so surely it can withstand the pressure?

It is the water supply to your taps/showers that matters going to vented to unvented.

(the radiator is a totally separate thing - that water in that goes round and round through your boiler inside your radiators....the new expansion vessel bit - I assume is to to account for the drop of pressure/increase in water volume caused having to feed extra radiators but it still shouldn't be particularly high pressure -if your pipe work was done properly it should be fine).
Assuming your cold taps are fed by water directly from the mains (not from a header tank - cold water tank in loft - your kitchen really shouldn't be, bathroom possibly might) they will be fine -no change in pressure.
It is the hot water feed to taps/showers that might cause a problem -and not just in plastic (which is fine now generally - it was the fact mine was bodged and ancient that caused problems) - weaker joins on copper can fail under the increased pressure - but you are more likely to get a leak rather than the hose effect I got as the feed pipes can't move as easily to spring completely apart. (I went for the copper because I was so traumatised!!)
And lots of taps/showers are suitable for either lower pressure (vented tanks) or higher (unvented or mains) - so worth getting that checked.
I do have really high mains pressure but iirc all my cold taps were all already on mains pressure. All my taps were fine except the separate shower (and that was fixed at their expense) and the bath mixer shower head being a bit dodgy...

I don't know if Thames Water still give a grant. And if they do it may be means tested or you have to prove lead content in water and that you cannot afford to replace.

The advantage with replacing lead supply pipe (in addition to the obvious of avoiding lead poisoning) is that old lead supplies become unstable over time ie the lead disintegrates slowly.
This can over time cause the lead to split and you will have water pouring out.
The stability of the lead isn't helped by the water companies supplying higher pressure now than the lead pipes were ever designed to carry.

If you're in a Thames Water area, you most likely will have between 3bar and 5bar mains pressure. And they supply a minimum of 1.5bar.

If your installer (Megaflo installer/plumber) is connecting the megaflo and system directly to the mains without a high pressure cold water tank, then your supply will be at least 3bar as a Megaflow needs a minimum of 3bar to operate effectively.

If you have less than 3bar and no cold tank, you need to rethink the Megaflo as it will not do its job effectively at all.

If you want to know about the pressure you need Pigletjohns tried and tested bucket filling test and a stop watch

Bit like ripping off a plaster. Do it now and then it's done and dusted.

Thanks, I thought the bucket filling and stop watch would measure flow not pressure? I have done it and it comes out at 10 litres per minute, half of what I believe is required for a Megaflo so upgrading the mains is a must

The bucket filling isn't obviously an exact science but if it fills slowly then clearly you have poor pressure (assuming you're filling from a cold mains fed pipe).

It would upgrade the mains however this may not be enough to service your megaflo.

I've got a megaflo in current house and a TW area and we reliably have over 3bar of pressure.

Our "new" house (currently being refurbed) is in a South East Water area and during some parts of the day we have over 3bar but during peak times (morning and evening) it's much less than that.

So for our new CH and HW system, I am having a TWS cold water tank installed to ensure pressure will be over the 3bar the megaflo needs. Otherwise I'd be paying good money for a Megaflo and some very expensive thermostatic showers only do find water drizzling out slowly in the mornings.

The Megaflo helps deliver hot water at pressure so that you get good pressure flow for your showers.

However Megaflo can't do its job if your mains pressure is poor.

Simply upgrading your mains pipe work may not be enough.

Phone Thames Water technical department and ask them what pressure they generally deliver in your area.

They may not be able to be specific but sometimes they can. It's worth a go.

Don't rely on a new mains pipe to solve the issue.

the bucket test measures flow not pressure.