What am I missing? Isn't a Megaflo just a fancy hot water cylinder?

SiD the Turtle · 31 Mar 2017 at 08:54

Hey chaps. My house we moved into late last year has an ancient heating system we're looking to replace once the weather settles down. It's a boiler and cold water tank in the loft connected to a small cylinder in the bedroom. Our heating bills have been crazy, which I think is a combination of heating up loads of water we don't use, plus old windows and no insulation.

My thoughts are to move to a combi system, assuming the pressure checks out. Everyone I speak to says 'OMG you have to get a Megaflo if you want a combi with decent shower pressure'. But as amazing as they sound, isn't this just returning to a slightly less complicated system of having a massive tank of water heated up that you may or may not use, just without the cold tank?

DXP55 · 31 Mar 2017 at 09:06

Do get a Megaflo -

DO NOT get a combi JMHO - If only I had known.

Your heating bills are due to no insulation and a old boiler system

mattyg · 31 Mar 2017 at 09:08

You don't have a combi AND a Cylinder. You'll have a heat only boiler and a cylinder (megaflo or other)

I think at 55deg water temp if I turn off our boilers the water in the tank would only lose 2 deg in 24hrs. So your not constantly heating it up as such.

When we moved in to our house we had 2 large Combi's 1 for downstairs and one for the upper 2 floors. I think it was costing about £9 per day for heating and water. Since moving to 2 heat only boilers and a HW Cylinder with secondary circuit HW (which pumps hot water past all our hot taps so we have hot water pretty instantly ie its only got to travel about a foot through the tap) our cost has dropped to below £6 per day.

Before you panic. Its a 5000 sq foot house. We run a business from home so we are there ALL the time and we are renovating so have had periods of very draftiness. Oh and I'll always crank the heating up before I put on a jumper..(so yes I waste heat)

If you want mains pressure HW then a Cylinder is pretty much the only way to go.

Relentless81 · 31 Mar 2017 at 09:28

Maybe the cylinder stat is faulty. What temp is the cylinder stat set to and whats the temp at the closest tap?

If its faulty your boiler will heat the water when it doesnt need

Participant · 31 Mar 2017 at 09:51

Op your question should be 'which unvented cylinder should I get'. It doesn't have to be a Megaflo, there are loads of others that are just as good.

Assuming your incoming main is at a sufficiently high pressure and delivers sufficiently high flow into the cylinder, it's the best option for high pressure water (hot and cold) throughout the house.

the_r_sole · 31 Mar 2017 at 09:55

It is exactly that, a brand name for a pressurised system, they really do make a difference as they don't lose much heat of the water is sitting in there, i actually went for the one size up from what we needed and it's not costing much to run

psd99 · 31 Mar 2017 at 10:30

I just got a megaflow do it do it! The shower is amazing

you will get mains pressure on both HOT and COLD water

But remember your incoming connection will need to have good pressure. The old iron pipes don't generate enough pressure.

Jez · 31 Mar 2017 at 11:23

I recently had an unvented cylinder installed, it is amazing. Every shower and outlet in the house is now equalised with mains pressure - totally revolutionary to us

megaflo as mentioned is just a brand of unvented cylinder.

robj20 · 31 Mar 2017 at 12:01

If your not sure if you want a cylinder or not, its very easy to later add one to a combi. You could then run just the bathroom off the cylinder and the kitchen from the DHW of the combi.
Were getting a combi soon as we want the extra space the cylinder currently occupies. We only ever need one output of hot water.

Participant · 31 Mar 2017 at 12:56

psd99 said:
The old iron pipes don't generate enough pressure.

You mean flow not pressure, and even then that's not necessarily true.

To be pedantic, pipes never generate any pressure; pressure is created by the water company's pumps and the potential energy of water within tanks higher than your house.

If you have a short run of old metal 5/8" pipe supplying your house at 7 bar, you'll still get enough flow for an unvented system to work.

glitch · 31 Mar 2017 at 13:32

Participant said:
Op your question should be 'which unvented cylinder should I get'. It doesn't have to be a Megaflo, there are loads of others that are just as good.

What are some other brands worth looking at? I'm thinking of binning my hot water tank for an unvented cylinder whilst I've got an empty house and can afford both the time and money to get the plumbing sorted out for the future.

Participant · 31 Mar 2017 at 14:57

glitch said:
What are some other brands worth looking at? I'm thinking of binning my hot water tank for an unvented cylinder whilst I've got an empty house and can afford both the time and money to get the plumbing sorted out for the future.

Personally I've got a Worcester Bosch and it seems good quality, no issues in its first year. Can't speak to any of the others but I think Gledhill are quite popular.

Adam · 31 Mar 2017 at 16:02

Megaflow is a brand. I got a worcester bosch unvented cylinder as it added an extra 2 years to the warranty of my worcester bosch boiler.

b0rn2sk8 · 1 Apr 2017 at 23:18

We have a un-vented setup and it has quite frankly made every shower not taken at home a complete disappointment.

Having decent pressure on the hot water means taking a shower is a pleasure.

Lucifurr · 2 Apr 2017 at 10:15

To me I would have thought that getting insulation and Windows would be a key priority especially if your current system is still working OK.

I couldn't get combi at my house due to water flow just being a little too low so had to stick with the old style heating system with cold water tank and hot water cyclinder. Although I have now had the water supply pipe to my house replaced due to finding a leak and that only took a day to do with using moling so don't let water flow rate be a hindrance.