Vented Cylinder and Pump

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I have been reading various threads about the pro's and cons of installing vented vs unvented systems, and it seems clear that unvented is the way to go if you have a decent water pressure and flow (>20 l/m).

But what if you don't have decent flow coming through and it is not viable/desirable to install a new supply pipe from the road? Would the next best option be to install a vented cylinder with a pump? I have read about accumulators, but if I don't have the right pressure to start off with then it sounds a bit hit and miss whether it would work.

Assuming noise and space aren't an issue, could you tell me the advantages / disadvantages of installing a vented cylinder and pump set? I am thinking of a water tank in the loft (with byelaw kit) + boiler and cylinder in a shed at side of house. The pump would be something like a stuart turner twin pump to supply the whole house, and WC's would have a direct feed from the loft water tank.

Advantages I can see are lower cost, ability to control water flow, and less annual maintenance for the cylinder (vs an unvented cylinder)

It would be great if this thread didn't turn into a accumulator/thermal store/combi argument, although any relevant comments appreciated.

thanks!
 
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First things to determine are static pressure and full flow rate. Most people that think they have a pressure problem have actually a flow problem. Doesn't mean you can't have a pressure problem though; some parts of London have incredibly bad leaking mains and thames water tend to reduce the pressure there to minimum allowable, to reduce losses.
 
First things to determine are static pressure and full flow rate. Most people that think they have a pressure problem have actually a flow problem. Doesn't mean you can't have a pressure problem though; some parts of London have incredibly bad leaking mains and thames water tend to reduce the pressure there to minimum allowable, to reduce losses.

Thanks bengasman. But what if it's already determined that static pressure and full flow rate are not at acceptable levels. Would you be able to give some advice on the vented pump solution?
 
It would be handy to know what the flow rate and pressure are to be able to get an idea what is needed and what is possible.
 
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It would be handy to know what the flow rate and pressure are to be able to get an idea what is needed and what is possible.

I think our pressure is around 2 bar with 12 l/m flow rate. I thought pressure and flow rate are not that important when considering a cold storage tank and vented cylinder solution? Property has 2 bathrooms, and max required flow rate would be 30 l/m
 
If the chap that determined your boiler should go in a shed is the same as the one who told you 2 bar is an unacceptable pressure, I would suggest you sack him and find someone who knows what he is on a about.
 
If the chap that determined your boiler should go in a shed is the same as the one who told you 2 bar is an unacceptable pressure, I would suggest you sack him and find someone who knows what he is on a about.

That may well be, but could I get some advice on a vented cylinder with pump set?

Thanks
 
Bog standard cylinder should do fine. If you are dissatisfied with the flow it produces, add a pump.
 
if space isint an issue, you should consider a break tank and pump supplying an unvented cylinder, keep the tanks in the loft to supply toilet cisterns and a seperate cold water main supply to kitchen sink.
 
if space isint an issue, you should consider a break tank and pump supplying an unvented cylinder, keep the tanks in the loft to supply toilet cisterns and a seperate cold water main supply to kitchen sink.

Wow! That costs!!! ...and he still has an annual service charge for the cylinder.

His best solution in technical and cost, is a vented thermal store or high flow combi and an accumulator. High pressure and no annual service charges.
 
It would be great if this thread didn't turn into a accumulator/thermal store/combi argument, although any relevant comments appreciated.[
 
It would be great if this thread didn't turn into a accumulator/thermal store/combi argument, although any relevant comments appreciated.

Good reminder. He got some relevant comment. He wants low installation cost, no annual service costs, reliability and high pressure to certain outlets, namely the showers and maybe the garden hose as a minimum. What I suggested will give him all that. I have done all this before and found this combination (either a high flow combi or thermal store) is by far the best. In space saved the combi/accumulator is by far the best. In DHW delivery and boiler reliability the thermals store, but takes up more space.
 
I have read about accumulators, but if I don't have the right pressure to start off with then it sounds a bit hit and miss whether it would work.
please completly ignore the op, your point of view is more important
 
I have read about accumulators, but if I don't have the right pressure to start off with then it sounds a bit hit and miss whether it would work.
please completly ignore the op, your point of view is more important

The OP is an amateur requesting advice. I detect information overload on his part. He needs guidance and suggestions on the optimum solution. I gave that, with the info provided I would say the best for him by far.
 

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