Horizontal Unvented Hot water cylinder or 2 smaller?

[Del1971]

Looking for some advice please!

We've just realised that our architect hasn't left us enough headroom in our loft conversion plans to fit in a reasonable size of hot water cylinder. Have asked our plumber to look into alternatives; either a horizontal cylinder or two cylinders running together). Does anyone have any experience of either of those setups? The plumber hasn't got experience with eithet.

We've got plenty of floor space (1.25m by 2.5m) in the cupboard but not enough height (max 1.375m for a 55cm diameter cylinder).

When the conversion is done we'll have a 6 bed/3 bathroom house (one bath and three showers) so we're looking for as much capacity as possible without being too inefficient. Was thinking 250-300l so a small vertical cylinder isnt an option.

We're replacing a gravity fed system with a new unvented one. Don't know what mains pressure is like, but flow is pretty good (filled up a 4 litre pot in 8 seconds).

Any advice gratefully welcome!

 

[simond]

Horizontal unvented;

http://www.telford-group.com/downloads/files/brochure_copper.pdf

Horizontal cylinders aren't ideal but clearly your situation falls into that category. It will still need to be accessible for maintenance. Get your architect to fit it.

Or fit a Worcester Bosch Highflow 550CDi , it'll offer a similar performance on your water main to the unvented and take up the space of a washing machine downstairs. The 550Cdi is effectively a combi with a small unvented inside.

I do wonder why people hire plumbers when they need experienced heating engineers.

 

[Del1971]

Cheers Simon,

The plumbers are sub contracted by the construction firm project managing the loft conversion. They've got a lot of experience of installing unvented systems with upright cylinders, but just haven't used horizontals before.

I'd checked out a few horizontal cylinders today on the net and I did fancy the Telfords. Thanks for the link.

I'll ask the plumbers to look into the Highflow.

Are the horizontals really that bad in terms of performance?

 

[sooey]

Can't you stick a proper one in the garage?

 

[SDMCF]

We have a 650 litre horizontal tank which was already in place when we moved here. This tank is no longer our primary source of hot water. We use it as a tempering tank before a new 300 litre upright tank. The upright tank is a lot better, but then it is also much newer and modern, so not a fair comparison.

Personally I would fit 2 smaller upright tanks, with the option of only using 1 when the house is not fully occupied. That would also give you some sort of back-up in case of problems with one of the tanks.

Remember that water is heavy. If your architect didn't leave enough space for a large cylinder then maybe the floor will not support that much weight. Check that before deciding what to get. Maybe 2 cylinders will be needed anyway to spread the load over a wider area.

 

[Del1971]

Unfortunately our garage is detatched and quite a bit away from the house with lots of paving stones in between, otherwise would have been a good alternative.

 

[Del1971]

Thanks guys for the replies,

I sent an email to our structural engineer yesterday to check the load bearing issue. He's known from the start that this space is going to hold a hefty water cylinder, so hoping he's had the good sense to build in the support.

We've got a couple of RSJs going in to support the loft floor (one running just along side the airing cupboard) and the joists are getting doubled up so hoping he'll get back saying this will be enough.

 

[philtheplumber]

I know i'm looking at this a few months late but to get a horizontal to perform as good as a vertical fit a Secondary return pump from hot out to cold in or if a secondary pump already fitted then put it back into cold in rather than the one provided on side of cylinder. This will enable the heat source to heat the cylinder to full capacity. I fit this and wire pump to two port so it only runs on heat up.

 

[dcawkwell]

I would suggest two smaller unvented cylinders spaced so that they are near the demands rather than one large one with longer dead zone between
tank and tap.

I think a 150 litre warmflow comes in at 1142mm high.

This would allow you to only heat one cylinder if only part of
the house is being used.

An alternative is a high delivery combi boiler or a high delivery combi and an unvented cylinder splitting the house again so supply is near demand.

Whoops I see this is an old posting.

 

[mysteryman]

All you need is a good quality horizontal cylinder. Don't worry about the rest of the concerns raised here!

 

[philtheplumber]

Horizontals have an inherent issue of stratification no matter what the quality.

 

[Dan Robinson]

Viessman won't sell their cylinder here either.

 

[Del1971]

Thanks for all the comments folks.

We've actually had a horizontal cylinder installed already and it seems to work really well (although I think anything would have been an improvement on our old system).

We've got a pressurised system with a Vaillant ecotec plus boiler and a 300L horizontal cylinder (Kingspan Tribune stainless steel 453mm dia vessel).

Couldn't tell you exactly how it's been plumbed in as I have no expertise in that side of things, but I have absolutely no complaints about performance. (We have 3 bathrooms one of which has a 301L bathtub and an overhead rain attachment in the shower).

 

[Agile]

Looking for some advice please!

The plumber hasn't got experience with eithet.


We're replacing a gravity fed system with a new unvented one. Don't know what mains pressure is like, but flow is pretty good (filled up a 4 litre pot in 8 seconds).

Any advice gratefully welcome!

"Plumbers" employed by builders are not likely to be the most experienced design engineers! They are better called fitters!

Anyone fitting unvented cylinders without checking the dynamic fow rate,( see FAQ ) is risking a severe problem.

You seem to have been lucky but have you used all three bathrooms at the same time???

Tony