Boiler Options for low flow rate mains

[jonnyiles]

I'm getting myself all confused. Can you guys give me the benefit of your experience.
I have an inlet flow rate of 14l/min - don't know the pressure.
I want to be able to run a shower and maybe a bath at the same time but this isn't essential. I just don't want to have the shower fizzle out if someone turns on a tap elsewhere in the house.
I have a 4 bed house with 1 bath - but soon to be 1 bath and 1 en suite.

I've looked at a megaflow but because the flow rate is low it doesn't make sense and I'll still only max out at 14l/min so I may as well have a combi.

If I run a combi could I get two showers running with 7l/min from each? or is it not that simple?

Why do I want a combi or megaflow - so i can get rid of my hotwater tank etc to fit a shower in the airing cupboard.

I looked at a glowworm storage SXI but can't work out whether this will help - I'm guessing not as I'll still max out at a flow rate of 14l/min and there's no point storing the hot water if you can only draw it off at the same rate that it can be produced?

Final question if you haven;t lost the will to live. If I get a combi put in is there anything stopping me using it with a vented or sealed system in the future?

 

[sambotc]

Hi,

Where did you have in mind siting a megaflow? Would it be suitable siting a vented cylinder in the same spot?

That would be my first recommendation if suitable.

 

[jonnyiles]

I want to put it all in the loft so I can free up the airing cupboard for a shower. Trouble is that my loft doesn;t have a great deal of height so I probably need a horizontal cylinder if it's vemted.
I would put a megaflow in but from my limited understanding it's not worth it because I can only get 14l/min out because my mains flow is only 14l/min so I may as well have a combi!
If I go for a combi can i use it with a vented in the future if I decide that this is what I need when my kids grow up?

 

[Happyplumber]

you will have to use a conventional system,unless you are willing to spend some money and have your mains upgraded,this will increase the flow rate,you need ideally 20 lpm for unvented cylinder to perform well


combi in such a large house is not ideal,call in local heating engineer who can do proper site survey and quote you in system which suitable for your needs

 

[jonnyiles]

I've had a couple of guys advise me and one said he would install a combi the other said I should go for a megaflow but I've since measured the flow and all agree this rules out a megaflow unless I upgrade the mains. I've looked into this and it's very expensive so I'm wondering if I can get away with a combi for now and then potentially use it to run a vented or unvented in the future? Or would I have to change the boielr as well?

 

[kitch0978]

how about an accumalator instead of upgrading the mains? not sure of cost of these...... others on this forum will know...its just a thought and i`m not well versed in unvented issues

 

[Happyplumber]

What you spend on accumulator and they can break down is probably more then it will cost to upgrade the mains

Yes the combi crew have been in i see

Call a proper time served plumbing and heating engineer in who has experience of conventional ,as well pressurised system not just chuck combi in and run crew

 

[sambotc]

Doesn't really matter where the cylinder is, as long as the cold water storage tank which feeds it (presuming its not a fortic cylinder) is in a suitable position ( ie higher than it and any outlets, and not in the way of your current plans)

Could you not reposition the cylinder anywhere else? Ground floor even?

Sam

 

[jonnyiles]

I may have somewhere else to put the cylinder. You've got me thinking now.
Any thoughts on whether I can use a combi with a vented cylinder. I thinking of getting a combi installed but then converting to a traditional system when demands increase as kids grow up! Or would I have to change the boiler again?

 

[jonnyiles]

I did wonder about an accumulator but I'm not too sure how this would help - can any of you experts give us a quick run down of what an accumulator can do?

 

[sambotc]

Hi,


You could use a combi in conjunction with a vented or unvented cylinder. The combi could provide instant hot water too one or more low flow rate hot water outlets (e.g kitchen tap, wash hand basin, washing machine etc) and the vented cylinder could provide HW for showers, baths etc.

HTH Sam

 

[kitch0978]

Hi,


You could use a combi in conjunction with a vented or unvented cylinder. The combi could provide instant hot water too one or more low flow rate hot water outlets (e.g kitchen tap, wash hand basin, washing machine etc) and the vented cylinder could provide HW for showers, baths etc.

HTH Sam

but still need 20 litres min for unvented to work well......?

 

[jonnyiles]

thanks for all your thoughts chaps, I think I'll go for a vented system and find somewhere appropriate for the cylinder.

 

[jonnyiles]

one more question on this thread guys if you are still watching. If I upgrade the mains pipe to 25mm will I need to run this all the way to the boiler or megalfow? I have 15mm copper pipes running from the stop cock in the house to the boiler, cold water tank etc - so am I wasting my time upgrading from the mains if it reduces down to 15mm copper after the stop cock?

 

[muggles]

Yes, you'll need to upgrade your 15mm to 22mm. If you can deal with the extra upheaval then ideally your new water main should be run into your cylinder cupboard, then the cold will come out of the connection on the balancing valve to feed the house