Pumping combination cylinder

[GQuigley67]

I know this is not recommended by manufacturer but hear me out, would like to pick your brains on this one.

1. Small flat 1x shower, only 1 person living, 210L combination cylinder with salamander pump? Surely it won't run out with the extra capacity?

2. Cold water is 2 bar so too low for UVHWC, so was looking at 2 bar pump.

2. She wants to free space in the cupboard so the 50 gallon minimum cold rank recommended by pump manufacturer will take up too much space.

3. No gas and I'm quoting for Electric wet system install so trying to keep everything compact to free up space.

I think it should be fine, but would like some other opinions? Any advice appreciated

 

[ShaunCorbs]

What's the flow like ? If it's acceptable I would fit an unvented cylinder (it's the bear min 2 bar)

 

[GQuigley67]

What's the flow like ? If it's acceptable I would fit an unvented cylinder (it's the bear min 2 bar)

Flow seemed decent enough

Top floor flat, flat roof above so no loft space, unvented operating pressure 3.5 bar so not sure about fitting it on 2 bar system, would need to speak to manufacturer on that one.

 

[tolly]

I would go unvented. Im not sure why some manu's say it must be fitted to a mains with 3 bar dynamic at 20l/min, obviously this would be the ideal for best performance, but i cant see a reason why they would be unhappy if the mains wasnt giving that. Other than maybe unknowledgable customers giving there product a bad name when its not actually the cylinder at fault but the water mains/installation being unsuitable.

There are loads of combis fitted on old 1/2 lead mains barely getting 1 bar with 10l/min and in your instance of a 1 bath property i would take the unvented over a combi any day.

 

[mfgs]

I would go unvented too. Check the flow rate is ok first though, is the 2 bar pressure standing or dynamic?

 

[cr0ft]

I know this is not recommended by manufacturer but hear me out, would like to pick your brains on this one.

1. Small flat 1x shower, only 1 person living, 210L combination cylinder with salamander pump? Surely it won't run out with the extra capacity?

2. Cold water is 2 bar so too low for UVHWC, so was looking at 2 bar pump.

2. She wants to free space in the cupboard so the 50 gallon minimum cold rank recommended by pump manufacturer will take up too much space.

3. No gas and I'm quoting for Electric wet system install so trying to keep everything compact to free up space.

I think it should be fine, but would like some other opinions? Any advice appreciated

1. It's the small cold water header tank on the combination cylinder you need to worry about running out, not the hot water cylinder itself. Any decent pump is going to empty that cylinder faster than the fill valve can fill it. End result is you will be sucking air into the pump at that point.

2. Agreed, if this is the static pressure then dynamic pressure is likely to be a lot lower. The reason unvented cylinders specify such high pressures and flow rates are to cover their backs when 2 or more outlets are run at once. Personally I wouldn't fit an unvented cylinder unless the water mains met manufacturers requirements.

Is it a single pump or a twin pump. If it's pumping cold as well how are you going to connect it into the combi cylinder? I'm assuming it's just going to be pumping hot?

Expect no warranty support though if there's a problem with the pump on a combination cylinder!

Best solution in my opinion would be a vented cylinder, new cold water storage cistern and a whole house pump/shower pump. Sometimes customers have to give on something!

 

[cr0ft]

Something that might be useful to do - time the fill rate of the cistern on top of the combination cylinder. Once you have that in Litres per minute, consult the pump pressure/flow rate chart for the pump you are looking to buy. If your cold water pressure is 2 bars then you will want to buy a 3 bar pump for the hot. Reason being, 3 bar is the static pressure that pump achieves. Once you open an outlet, the 3 bar pump will deliver water to the shower at 15L/min at 2 bars. That's about where you want to be I'd suggest for a pumped shower. That's using the curve below which is for a twin pump. Obviously if using a single pump use the relevant chart.

If the fill rate is higher than the pump flow rate there shouldn't be an issue really. If it isn't then you need a different cylinder really.

 

[GQuigley67]

Mains is 2 bar static, so I'm not too keen on fitting unvented. Any one know of any combination electric cylinders?

 

[townfanjon]

Mains is 2 bar static, so I'm not too keen on fitting unvented. Any one know of any combination electric cylinders?

Rm do the Flowtherm , looks a bit antiquated by todays standards , but is usually in a cupboard so it doesnt matter .
The other one I instal is the Elson Aquanox

 

[GQuigley67]

Coral aquanox thermalstore? Is it compatible with electric boiler ?

 

[ShaunCorbs]

Fit one of these

2 bar and 15lpm incoming (old lead 1/2)

All working fine and cus happy

 

[townfanjon]

Coral aquanox thermalstore? Is it compatible with electric boiler ?

Sorry I didnt read everything, just saw you needed an electric combi cylinder , apologies

 

[GQuigley67]

Fit one of these

2 bar and 15lpm incoming (old lead 1/2)

All working fine and cus happy

View attachment 29809

View attachment 29810

What system is that?

I spoke to McDonald engineers and they've said a thermal store powered by Immersers, dimensions 1700x550 which is ideal for the space I have, heating output is 7700 Watts and their thermal store can do upto 12kw.

 

[ShaunCorbs]

What system is that?

I spoke to McDonald engineers and they've said a thermal store powered by Immersers, dimensions 1700x550 which is ideal for the space I have, heating output is 7700 Watts and their thermal store can do upto 12kw.

Trianco Aztec Easyfit 12kW All in One Heating System