can someone explain which is better (cylinder question)

[ghost32]

moving the cylinder in our house into the loft, I'll need to be going for a new horizontal cylinder, so you can have the 1m height water tank above it. ( going to box it all in to minimise the heat loss, but i have been looking at cylinders and there's a few things i still don't understand
1. what's the difference between vented and unvented
2. which one is better?
3. the hot water cylinder feeds all hot water in the house ( I will be changing the bathroom at some point and adding a decent shower but i want it to fire water out so i need to get one of those pressure pumps /water booster (do i need to take this into account when choosing the cylinder)

http://www.discountedheating.co.uk/shop/acatalog/Telford_Horizontal_Cylinders.html
this is the cylinder i've seen does anyone have an opinion on this whether there's better out there
( i like in a 3 bed end of terrace) 2 bathrooms 0 kids.. yet :/

thanks
Mark

 

[gas4you]

Be careful putting a vented cylinder in your loft. You must maintain the head of water from the cold storage tank above the new cylinder position.

The unvented cylinder is a mains pressure cylinder which has no vent to atmosphere. They are available in various sizes but I do not know of any that can be horizontal. Hot water performance is a lot better with these as lomg as you have good incoming cold mains pressure. ideally around 4 bar or so. Installing one of these will probably create more work as the cold for any showers etc has to be taken from the cylinder side of the pressure balancing vale. They also need to be fitted by a registered unvented qualified installer. You would not need/be able to have a shower pump with one of these. Visit here for more info http://www.heatraesadia.com/hs/heatraes.nsf

 

[EliteHeat]

but I do not know of any that can be horizontal

The OP's link was for an unvented horizontal cylinder

 

[ChrisR]

There would be no need for it to be horizontal if there's enough height for it to stand up. An unvented cylinder doesn't need a header tank.

Unventeds only work if there's good mains pressure AND flow - no point putting one on a high pressure mains coming through a half inch squashed lead pipe.

WIthout any new mains pipe, an unvented will work out a few hundred £ more expensive than putting two new tanks in the loft, but you wouldn't need any pumps, which saves on noise, maintenance, leaks, and their cost.

There's often little or no point using the "balanced" cold water feed. Only for very high mains pressure really.

Before you decide anything you need to find out your mains pressure and flow.

 

[Nige F]

moving the cylinder in our house into the loft, I'll need to be going for a new horizontal cylinder, 1. what's the difference between vented and unvented

[
thanks
Mark

...Vented you can install yourself ..........unvented, you can`t install unless with a "ticket" for unvented

 

[gas4you]

but I do not know of any that can be horizontal

The OP's link was for an unvented horizontal cylinder

sorry I forgt to check his link!!

 

[Agile]

I do think that a cold feed from the regulated side is very worthwhile for the shower as it gives a much more stable shower adjustment.

Thats something I would always do in my own home so....

As far as I can see from the regulations, unlike gas work, it IS possible for an unvented cylinder to be actually fitted by a DIY as long as its checked and commissioned by an unvented qualified person before being used.

I would be happy to commission one if anybody ever were to ask.

Tony

 

[ghost32]

ok i'm kinda getting this

So how would i be able to test/measure the mains pressure
I'm guessing i'll need to do it as close as possible to where i'll be putting the new tank.


I like the idea of unvented as it will able me to put a vertical one in the loft next to the chimney stack and not have the need for a shower pump as the pressure will be allot better.


also 1 other quick question what's the difference between direct and indirect unvented cylinders

 

[Agile]

You need to measyre the FLOW rate in litres per minute !!!

I always advise it should be at least 25 li/min to an open pipe to justify fitting an unvented.

Anything less and it will work but the flow rate is likely to be little better than a combi would be able to give.

Tony

 

[gas4you]

You need to know the incoming mains pressure/working cold mains pressure other wise how do you know if ther is enough pressure for the pressure reducing valve to work correctly and balance the take off points. This is why I always hope to see approx 4 bar, so after pressure reducing valve reduces it to 3 bar then you still have 1 bar available for the balancing process. If you only have 2 bar for example the system will not give balanced take off points.

Most PRV's supplied with unvented cylinders are factory set at 3 bar

 

[Agile]

Perhaps you are so lucky in Norwich but most of London has more like 1.5 Bar for most of the waking hours!

Its still balanced though if connected that way to the shower even if the incomming pressure is below the PRV value.

Tony

 

[gas4you]

most areas of Norwich are lucky to have at least 2 bar. Some outlying country aresa I work in have had 7 bar when I have tested it. Blows your socks off!!!

 

[tessie]

I do think that a cold feed from the regulated side is very worthwhile for the shower as it gives a much more stable shower adjustment.

Thats something I would always do in my own home so....

As far as I can see from the regulations, unlike gas work, it IS possible for an unvented cylinder to be actually fitted by a DIY as long as its checked and commissioned by an unvented qualified person before being used.

I would be happy to commission one if anybody ever were to ask.

Tony

 

[Onetap]

6 year-old dead thread.