Proposed Grant Vortex Pro Installation

[dave12]

Hi,

I'm about to embark on a full Heating / HW system upgrade. However, there is one thing that is bothering me most. Whilst I am relatively happy at the choice of Boiler, I am unsure about the type of System I should be installing. Vented or unvented.
My current system is a vented system which seems fine. But the pressure / flow doesn't seem great.
I know that the Unvented system would give me mains pressure on the Hot Water. But My concern is whether I have sufficient flow. I have tested this (Bucket & watch method) and found the flow rate to be ~15l/min or 10l in 40sec. But, if I do the same test with another tap flowing then this drops to 12l/min or 10l in 50sec. Is this enough?
What I don't want to lose is our good shower. This is obviously supplied via a pump at the moment, which I wouldn't be able to have in a unvented system. So would my flowrate be sufficient?

Or, should I stick to what I have, a Vented system. It doesn't bother me about having tanks in the loft. Although will be looking to remove a Cold Water tank thats feeding all taps except for the kitchen! (different job).

Cheers

 

[muggles]

If that's all the flow rate you've got and you want mains-pressure hot water you'd be better off with a combi boiler

 

[dave12]

Hi Mugggles,

Thanks for responding.

Isn't a Combi worse when there is a high demand for water? I have had a combi before in a previous house and there was no way you could run 2 taps for hot water at the same time as the pressure was dreadful. I also seem to remember it taking an age to run a bath. And the flowrate was far better in that house?

This new place has 3 bathrooms, so have been recommended an unvented system. Although I'm not sure about the thinking on this one.

Not sure if its worth mentioning also that this is an Oil fired Boiler.

Cheers

 

[muggles]

You'll get 15l/min out of an oil combi, an unvented cylinder isn't magically going to give you a higher flow rate than is coming in.

Having said that, there are ways to do it. I've got a similar situation in my house and have cured it by fitting a 100 gallon tank in the loft and pumping water out of that into an unvented cylinder, so we now have a potential 90l/min @ 2.0 bar. It's not cheap to do but worth it if you do need a good flow of hot water. Pump the cold as well to ensure balanced flow & pressure at your mixed outlets

 

[Boilerman2]

Unvented cylinder linked to an Accumulator vessel would do it!

gah Coldstream or dualstream for example

 

[muggles]

Unvented cylinder linked to an Accumulator vessel would do it!

gah Coldstream or dualstream for example

You're assuming his static pressure is good....

 

[manortim]

Leave it as is. Nothing wrong with good old fashioned stored water with vented cylinder.

Plus....oil combis are rubbish. Void like aids!

 

[dave12]

Thanks for all the replies!

I guess the biggest worry for me installing the unvented system is having cr@p showers. We currently have a power shower which is pretty good, (although it has its floors (another story)).

If I hook up a shower head to the mains water would this replicate the kind of pressure / flow I would get if I went for unvented? I could then turn on another tap to simulate a toilet flush or a washing machine being on etc to see how bad it gets.

If I chose to stick with Vented, is it worth changing out the current Hot Water tank? It looks pretty modern. Well its foam insulated. Are there any big benefits with new Tanks?

I'm beginning to think that I could just install the new boiler as is, then convert in the future when I am in a position to run in a new Main to the house.

 

[manortim]

Boiler wise.

Consider hounsfield Tuscan boiler.