Discuss Big changes planned... and a few questions in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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vetinry

Evening everyone.

I'm just about to embark on a major change to the heating and hot water and have a few questions before work starts.

Current system is oil powered gravity fed hw and y plan system. The house is over 300sq metres and last year's oil bill was not far off £2.5k. On top of this, the cylinder is only 140 litres and is crammed into the eaves of upstairs with a broken immersion heater.

There are a couple of key reasons why I want to change things:

Firstly, If oil prices increase as expected, I would like to reduce my reliance on it.
Secondly, the current y plan system doesn't allow much in the way of control of heating in the property and since we've recently installed ufh in the kitchen, I would like add some zones.

The plan

Can't get a bigger cylinder into the current area so creating an insulated room in the garage.
Change to an unvented cylinder and going to try an ecocent to see if I can achieve some savings on my energy bill (hopefully not just a reduction in oil bill but corresponding increase in electricity bill).
Change from Y plan to S plan plus with 3 zones (downstairs, upstairs and UFH) and water.

Questions

The property appears to have 2 main supplies. The main one comes in under the sink (28mm? OD MDPE) and provides water to kitchen utility and tanks in top loft.
However, there is a second MDPE pipe (20mm OD?) in garage, where we'd like to site the tank.
I've measured static pressure of approx 3.5bar at each of these and it doesn't appear to drop much if I switch on kitchen / utility tap.
I've then timed filling up a 3 gallon bucket and it takes approx 30 seconds at both supply point, which I've therefore calculated at approx 25 litres per min. Again, this doesn't seem to drop much with the kitchen and utility tap on full.


There are 3 showers in the house, and each is currently running of its own shower pump. All the pipe work is 22mm, apart from the secondary circulation which is 15mm, and so unfortunately is the mains supply upto the top loft from the kitchen.

So, I'm wondering whether I can use the kitchen main to supply the cold water, and the garage main to supply the unvented cylinder and therefore the hot water.

Are there any fundamental reasons not to do this, and from what I've measured for pressure and flow, am I likely to enjoy showers as much as I do now (until the water runs out).

All help / comments very gratefully received.

Steve
 
It'd be a waste not to wouldn't it? One thing you could consider is maintaining equal pressure, vetinry. That'd be my only concern. Fitting pressure reducing valves to both with gauges etc. will allow you that guarantee I'd say... IMO
 
As diamondgas says prvs to ensure balanced supplies. You'll enjoy better showers, what size unvented cylinder are you going for?
 
Thanks for the replies.

I think I understand about balancing the supplies - they both appear to be showing 3.5 bar on a static test, and this didn't seem to change when I turned the taps on. Mind you, it was only a cheap pressure gauge.

So, ideally do I need to put a gauge on each of the inlets and then when the system is up and running use them to balance.

Does the overall system pressure need reducing below 3.5 bar? I know that the plumber will sort this, but obviously I'm keen to have as good showers as possible. Will I notice a difference in shower quality between what I have now (gravity and pump) and what I'm proposing - should I check the current flow rates to know what I can expect.

And in terms of overall flow, is it as simple as adding the flow from the cold and hot supply together, allowing for blending ratio?

The ecocent unit only heats the water to approx 45 - 50 degrees so I guess I won't be using much cold and therefore flow rate will be 25 litres per minute max.

In terms of cylinder size, I'm thinking of 300 litres. 5 bed, 3 bathroom, and since there will only be an ASHP heating the water, I wasn't sure how quickly the tank would be replenished so thought I should have plenty available.

Is this a sensible assumption?

Thanks

Steve
 
vetinry (Steve) - Opening this one up to see if there's anyone here to best advise ... Over to you chaps :)
 
Its just my opinion and to be fair I dont personally install Solar thermal but having spoken to the guys at Secon Solar last week in Manchester Id seriously give thought to investing in a solar panel kit. If the sun was shining like it was on Sunday you'd have a 300l twin coil cylinder brimming full of 75 degree water all day at the cost of running the circulating pump, which is a famn site cheaper than using oil !
 
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