Unvented cylinder, heating/water system, pressure

[Enski]

Hello all from Manchester,

We've suffered from low pressure in our home for over 20 years - to such an extend that water from the shower would come out so low it takes minutes just to get properly wet. We tried various solutions but finally we are moving away into a new home.

I know nothing about plumbing/water systems but I have done *a lot* of reading over the last few days in an attempt to learn what we should do in our new house.

I've learnt that if the pressure/flow rate from the external pipes is good enough, the best system is an unvented cylinder. I do have some questions still which I cant find answers for:
1) Can these things be powered by gas?
2) If they are electric, and as they seem to keep the water in the tank heated at all times, is this not very costly?
3) Can an unvented cylinder (such as 300L Megaflo Heatrae Sadia) also do the heating in the house (radiators)? Does this mean that one such cylinder will do the job for everything?
4) Is there a list of approved Unvented Cylinder installers, or some place I can find somebody competent from?

Lastly, any advice or suggestions would be greatly appreciated.

 

[dcawkwell]

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We tried various solutions but finally we are moving away into a new home.
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Shame I could have sorted it. For a price.




1) Can these things be powered by gas?

The unvented cylinders are just like a conventional copper cylinder only
under mains pressure. Heated by a boiler indirectly or via immersion heater or both.

2) If they are electric, and as they seem to keep the water in the tank heated at all times, is this not very costly?

You only need to heat them when you need to water.
We have ours on to heat up in the morning for an hour and that provides enough hot water for two of us for the whole day. It then heats up for an hour in the evening. We have a 150 litre cylinder.
Modern tanks reheat from cold in a very short time though only 30 minutes so it isn't a problem.

3) Can an unvented cylinder (such as 300L Megaflo Heatrae Sadia) also do the heating in the house (radiators)? Does this mean that one such cylinder will do the job for everything?
You are getting confused with a thermal store. Here this supplies the central heating and hot water. Again heated by a gas/oil boiler.
The better configuration would be the boiler heats the central heating.

4) Is there a list of approved Unvented Cylinder installers, or some place I can find somebody competent from?
If you check the gas safe register you can verify that the installer has the unvented cylinder ticket. Like mine below.

Domestic area of work:
Unvented Cylinders
Gas Boiler
Combustion Analysis
Cooker
Fire
Pipework
Meters
Range Cooker
Water Heater

 

[Enski]

Thanks for your response. I'm still a little confused

This product, Heatrae Sadia Megaflo Eco Direct Unvented Hot Water Cylinder - it could provide the hot/cold water to the taps/shows/baths in the house?

For the heating (radiators), we would need to get a traditional boiler?

So we would have 2 separate systems? I understand that you can get cylinders which can be heated by an external source.

 

[dcawkwell]

Thanks for your response. I'm still a little confused

This product, Heatrae Sadia Megaflo Eco Direct Unvented Hot Water Cylinder - it could provide the hot/cold water to the taps/shows/baths in the house?

For the heating (radiators), we would need to get a traditional boiler?

So we would have 2 separate systems? I understand that you can get cylinders which can be heated by an external source.

The direct cylinder indicates it is heated by an immersion header.

You will need an unvented indirect cylinder. Inside this will be a coil of copper pipe that will be heated and therefore heat the hot water in the cylinder.

A gas boiler will heat the water in the central heating pipes and radiators as well as the water in the coil inside the unvented indirect cylinder.
A typical conventional house set up in the UK.

 

[muggles]

Thanks for your response. I'm still a little confused

This product, Heatrae Sadia Megaflo Eco Direct Unvented Hot Water Cylinder - it could provide the hot/cold water to the taps/shows/baths in the house?

It would provide the hot water to all outlets, the cold would come from your mains

For the heating (radiators), we would need to get a traditional boiler?

Yes, but presumably you already have one of those?

So we would have 2 separate systems? I understand that you can get cylinders which can be heated by an external source.

Your hot and cold water are separate systems to your heating whatever you do, the cylinder would as you say normally be heated by an external source (boiler)

 

[Enski]

It is a gutted house and we are having to do everything from scratch including all pipework and boilers/cylinders.

I will call in a professional then, somebody who is registered on gassafe with the 'Unvented Cylinders' tick, and tell them that we need an unvented cylinder with a boiler, and hope like hell he is competent enough to provide us with a problem free service/set up.

One last question - how does the boiler heat the water that the cylinder holds. From what dcawkwell said, hot water travels into the 'coils' in the cylinder from the boiler, and heats it up this way. Seems to me very inefficient and slow, but I readily admit to knowing nothing about it.

 

[Enski]

While I am here, can anybody recommend any brands? I have heard Vaillant are good, and all I know for the unvented cylinder side of things is Heatrae Sadia's Megaflo.

 

[muggles]

daculkwell has correctly described how the cylinder is heated, it's not at all inefficient or slow, in fact it's quite the opposite. As to which cylinder to get, personally I'd recommend the OSO Super S, which has very fast reheat times, is very well insulated, is easy to install especially when starting from scratch and also looks extremely neat - if installed to the instructions you won't see any pipework at all from the front. Generally a little cheaper than a Megaflo and IMO a better cylinder

As for brand of boiler, your installer will have one he normally uses and may well be able to offer a free extended warranty on. There are still good and bad ones mind, but a lower-grade boiler installed well should still outlast the best boiler installed badly. Of course, the ultimate is to find a good installer who will put in one of the best boiler makes. Vaillant, ATAG and Intergas are all good, although you may struggle to find an Intergas Platinum 5 installer, we're still a rare breed!

 

[flameport]

hot water travels into the 'coils' in the cylinder from the boiler, and heats it up this way. Seems to me very inefficient and slow, but I readily admit to knowing nothing about it.

It's far quicker than using an electric immersion heater, and much cheaper as well.

 

[Enski]

Thanks all, very much appreciated.

What I've realised is that many of the 'plumbers/installers' in our area don't actually know how to install an unvented cylinder system and therefore they are forever recommending combi boilers - its the only thing they know. I've checked gassafe and know how to find somebody who can install them, I'll be calling somebody out within days.


I'm actually really looking forward to having a decent water system in the house. Not only was our pressure non-existant (resulting in long showers), but the minute another tap was used, the pressure would halve. This caused a lot of problems in our household. On top of this, water was always going from hot to cold every minute or so, and I've developed a habit of automatically reaching for the mixer tap to adjust the hot/cold feed.

We'll get a brand new system installed in the new house, with a new cylinder, a new boiler and new radiators.

Have there been any developments with radiators or other technology, or am I safe to simply go to B&Q or some second hand place, and grab half decent ones?

 

[Enski]

I have just realised - everthing is dependant on the external water supply - if the flow rate/pressure isnt good enough, I will have to scrap this whole idea and go with something else.

Fingers crossed!