Why are Cylinders rarely in the loft for Trad. Gravity Vented Systems?

[Ric2013]

Do it the Centre for Alternative Technology way and have a removable roof panel that allows easy access from above? 😉 True story.

 

[GasAt300Bar]

You also have to calculate the height of the vent pipe above the cistern (and the f&e cos they NOT the same) so must be taken into account when looking at the max height of the cistern.

I was ponderin' that one. Water won't form a point, it stays stubbornly level. But the roof does, I can pitch the vent in this space. It's tight, but not impossible.

 

[Welder]

Shower pumps in my experience (which is small) are poor. Combi never in a million years. Storage Combi possibly but not in a loft. Unvented system yes. It will perform and be more effective than most other options

With a poor incomer, it is possible to have a high pressure unvented but you need a pump on the output from a big cistern feeding it. That cistern can be located anywhere (so long as you have a couple of flapper type non return valves in the output to stop back flow and you have seriously sized overflow on the tank just in case.

Doing it that way put the weight somewhere much safer.

 

[Welder]

I was ponderin' that one. Water won't form a point, it stays stubbornly level. But the roof does, I can pitch the vent in this space. It's tight, but not impossible.

That may be more than 350 above the cistern tho

 

[Ric2013]

That may be more than 350 above the cistern tho

I suppose if the OP has 350 above the sides of the access hatch, one side or the other will necessarily be under part of the slope and not the apex. Going to the ridge board could gain at least 6" (152mm).

 

[GasAt300Bar]

With a poor incomer, it is possible to have a high pressure unvented but you need a pump on the output from a big cistern feeding it. That cistern can be located anywhere (so long as you have a couple of flapper type non return valves in the output to stop back flow and you have seriously sized overflow on the tank just in case.

Doing it that way put the weight somewhere much safer.

So let me have this right. I put large tanks where I like, supply a sealed system pumped from this. I'm no fan of storing all that weight in my loft, and it won't be cheap or easy. If I go the sealed route, I've water at the pressure of my supply pump, stored somewhere safer? I can still move my HW tank into the loft, or anywhere really, but I've lost the massive CW tank in the loft. CW tank is now a supply tank placed any where I like as well? Have I got it?

 

[fixitflav]

That is a killer. With that requirement I'd need a horizontal cylinder.

I believe the cistern referred to there is the cold water tank. The (traditional type) hot water cylinder doesn't have a float valve.

 

[Ric2013]

I believe the cistern referred to there is the cold water tank. The (traditional type) hot water cylinder doesn't have a float valve.

I think he's thinking of a way to get more space above the cylinder by having the cylinder horizontal.

 

[GasAt300Bar]

I believe the cistern referred to there is the cold water tank. The (traditional type) hot water cylinder doesn't have a float valve.

Yes, I'd need a horizontal cylinder to get headroom for the CW tank/ cistern above it?

 

[Welder]

So let me have this right. I put large tanks where I like, supply a sealed system pumped from this. I'm no fan of storing all that weight in my loft, and it won't be cheap or easy. If I go the sealed route, I've water at the pressure of my supply pump, stored somewhere safer? I can still move my HW tank into the loft, or anywhere really, but I've lost the massive CW tank in the loft. CW tank is now a supply tank placed any where I like as well? Have I got it?

Yep

 

[GasAt300Bar]

Thank you . So in conclusion, a sealed-system's big advantage if I can find mains pressure to run it, is that,

1) Whilst some locations are better, at a push, I can put tanks broadly where I like.
2) In my case the HW tank will still find its way into the loft, simply because that's where there's space, (and gravity helps feed F & R to it too) but it could sit on the ground floor, next to the boiler, or even below it?
The downside is complication and getting a 'bloke' in.

Whereas a trad. system struggles to find loft-headroom, and weight is the worry. But at push, might be possible.

 

[Welder]

Thank you . Whereas a trad. system struggles to find loft-headroom, and weight is the worry. But at push, might be possible.

Just a fact for you. NO new house builder puts in low pressure systems anymore - not one. An HP system will also affords you a wider choice of kit to use. An LP system can work out expensive in things like showers as they have to be so much better machined.

 

[BYP]

Overall, yes an unvented system ( sealed) is leaps and bounds better, although vented systems are still very common and have a use as it were.

 

[Mark K]

Just a fact for you. NO new house builder puts in low pressure systems anymore - not one. An HP system will also affords you a wider choice of kit to use. An LP system can work out expensive in things like showers as they have to be so much better machined.

But they also put in mains feeds with sufficient capacity and pressure.

 

[GasAt300Bar]

Thanks all.

An HP system will also affords you a wider choice of kit to use. An LP system can work out expensive in things like showers as they have to be so much better machined.

How is that? I'd have it that a 'pump is a pump', I can see, if said pump was already fed at 1bar, it has less work to do, so we see more 'grunt' for our trouble, but what am I missing? Is that the only reason we need better kit?

 

[Welder]

Let's take an example. Mira hi pressure digital showers cannot work with pumped low pressure systems. However, do what I'm suggesting and they do work as it becomes a high pressure system.

Better kit = improved flow rates and they are required for NON pumped systems - gravity systems.

 

[fixitflav]

Mira hi pressure digital showers cannot work with pumped low pressure systems.

Better kit = improved flow rates and they are required for NON pumped systems - gravity systems.

I don't know what you're saying there. Can you please reword it for my benefit?