# Can the hot press tank be moved to the attic



## ice (7 Jan 2011)

Hi 

I am not sure of the correct terminology but is it possible to move the water tank thing in the hotpress to the attic ?

We are renovating our bathroom and getting the tank (boiler ?) to the attic would give us so much more space.

Can this be done?
Is it a big job?
Any idea how much extra money this would involve?

Many thanks


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## johnnygman (7 Jan 2011)

Your tank will certainly be exposed then to colder air and will lose more heat and consume more energy to keep warm water, it would also be an aditional risk in terms of freezing in winter in addition to your water tank.. Cant see these cons including cost of moving it being worth it ice..


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## Leo (7 Jan 2011)

The feeder tank would need to be above the hot water tank again. It's the difference in heigth (head) that creates the pressure to force water into the hot water tank, and subsequently out of it and to the taps.
Leo


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## SparkRite (7 Jan 2011)

Leo said:


> The feeder tank would need to be above the hot water tank again. It's the difference in heigth (head) that creates the pressure to force water into the hot water tank, and subsequently out of it and to the taps.
> Leo



Not entirely true Leo, its where the outlets (taps) are that matters and I assume these wont be moved into the attic, so therefore the header pressure will stay the same.
But you are right in saying that the cylinder would need to be below the header tank to initially fill the system, unless a syphon effect is initiated.


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## DGOBS (7 Jan 2011)

Or when moving it you could change it to an unvented cylinder thus eliminating the header tank altogether!


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## Barney Magoo (8 Jan 2011)

johnnygman said:


> Your tank will certainly be exposed then to colder air and will lose more heat and consume more energy to keep warm water, it would also be an aditional risk in terms of freezing in winter in addition to your water tank.. Cant see these cons including cost of moving it being worth it ice..



I doubt that this is a concern. Most modern ones come with insulation fitted. They are so well insulated that they don't transmit much heat to a hot-press/airing cupboard anyway and are largely a waste of space in that cupboard. We moved our tank into the attic for this reason giving us more cupboard space, and fitted a small radiator to the back of the cupboard to air the clothes instead.


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## Shane007 (8 Jan 2011)

SparkRite said:


> Not entirely true Leo, its where the outlets (taps) are that matters and I assume these wont be moved into the attic, so therefore the header pressure will stay the same.
> But you are right in saying that the cylinder would need to be below the header tank to initially fill the system, unless a syphon effect is initiated.


 
Sorry, but Leo is absolutely correct. The position of the taps have nothing to do with it if the hot water cylinder is gravity fed from the cw storage tank in the attic. The pressure at the taps is determined but the head height from the outlet of the hw cylinder (usually at top of cylinder) to the outlet of the cw water cylinder (usually bottom of tank). Raising the cw storage tank will increase the pressure. This pressure will be 0.1 bar of pressure per meter of head height between them.
Therefore, if you move the hw cylinder to the attic, there will be a significant decrease in pressure and mostly likely, none at all, as there will be no pressure into the cylinder to force the hot water out. The only way around this will be to pressurize the whole system but you will also need to pressurize the cold also. As DGOBS correctly says, you will have to change the cylinder to a pressurized cylinder, usually made of stainless steel, install pressure relief valves/pressure reducing valves, expansion vessel and a discharge pipe with tundish from the relief valve.


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## SparkRite (8 Jan 2011)

Shane007 said:


> Sorry, but Leo is absolutely correct. The position of the taps have nothing to do with it if the hot water cylinder is gravity fed from the cw storage tank in the attic. The pressure at the taps is determined but the head height from the outlet of the hw cylinder (usually at top of cylinder) to the outlet of the cw water cylinder (usually bottom of tank). Raising the cw storage tank will increase the pressure. This pressure will be 0.1 bar of pressure per meter of head height between them.
> Therefore, if you move the hw cylinder to the attic, there will be a significant decrease in pressure and mostly likely, none at all, as there will be no pressure into the cylinder to force the hot water out. The only way around this will be to pressurize the whole system but you will also need to pressurize the cold also. As DGOBS correctly says, you will have to change the cylinder to a pressurized cylinder, usually made of stainless steel, install pressure relief valves/pressure reducing valves, expansion vessel and a discharge pipe with tundish from the relief valve.



Yeah, the more I think about it, you are correct in most of what you say, I was in a rush when I composed my reply and didn't stop to really think about it.

The one issue I have is where you say:-



Shane007 said:


> The  position of the taps have nothing to do with it if the hot water  cylinder is gravity fed from the cw storage tank in the attic.



If a tap is level with or above the level of water in the header tank (as in an attic conversion for example) then no water will flow (without being pumped), no matter what the header pressure is at the cylinder, so I stand by what I said when I stated that the position of the taps does have a bearing on it.

But I am open to be corrected.........


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## Shane007 (8 Jan 2011)

Of course you are correct. A tap located above the cold water storage tank in the attic that is being fed by that tank will have no water flowing through it. It is gravity after all. In an attic conversion, the cw storage tank would have to be raised to a new height.


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## ice (8 Jan 2011)

Shane007 said:


> Sorry, but Leo is absolutely correct. The position of the taps have nothing to do with it if the hot water cylinder is gravity fed from the cw storage tank in the attic. The pressure at the taps is determined but the head height from the outlet of the hw cylinder (usually at top of cylinder) to the outlet of the cw water cylinder (usually bottom of tank). Raising the cw storage tank will increase the pressure. This pressure will be 0.1 bar of pressure per meter of head height between them.
> Therefore, if you move the hw cylinder to the attic, there will be a significant decrease in pressure and mostly likely, none at all, as there will be no pressure into the cylinder to force the hot water out. The only way around this will be to pressurize the whole system but you will also need to pressurize the cold also. As DGOBS correctly says, you will have to change the cylinder to a pressurized cylinder, usually made of stainless steel, install pressure relief valves/pressure reducing valves, expansion vessel and a discharge pipe with tundish from the relief valve.



Thanks for all the replies, much appreciated. The option you have described above, would it be a big job? Would it be expensive ?


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## Shane007 (8 Jan 2011)

ice said:


> Thanks for all the replies, much appreciated. The option you have described above, would it be a big job? Would it be expensive ?


 
Yes it would be a fairly substantial job. First you will need to decide on what size of hw cylinder you require. Then calculate the loading and see if your ceiling joists are large enough to carry this additional weight and of course is there enough height in the attic to site the cylinder. Secondly, be aware that you will require something like a 4 bar pump, which are pricey enough. Monsoon pumps are probably best and will cost in region of €400. You should also note that everything will be pressurized and when you flush a toilet the pump will run. Open any taps, the pump will run. Stainless steel cylinders with pressure kits are quite expensive too.
If you can find an alternative, I would, such as move it else where on that floor.


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## bstop (9 Jan 2011)

I think Sparkrite is correct regarding the head pressure being determined
by the position of the taps rather than the position of the cylinder.

Provided that the top of the cylinder is below the level of the bottom  of the cold water tank what you effectivly have are a pair of storage  tanks piped together. The lower one just happens to have a lid and an  expansion pipe on top. The head pressure is from the water level of the  upper tank ie the cold water tank, to the taps. The lower taps will have  a greater head than the higher ones. 

Imagine the cylinder as just a fatter piece of pipe and imagine the pipe  runs from the cold water tank as an s bend (with a vertical expansion  pipe) feeding down to the taps. The pressure at the taps is not affected  by the position of the fat s bend.


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## Shane007 (9 Jan 2011)

In gravity fed systems, the cw storage tank feeds the cw taps, showers, etc. except for ones that are fed from the mains. All taps must be below the outlet of the cw storage tank to achieve a pressure. This pressure will be determine by the distance in head height between these two. Different taps may will have different pressures as they may have different head heights. I am referring to cw taps only.
For hw taps, the pressure will be determined by the distance between the outlet of the cw storage tank and top outlet of the hw water cylinder. The hw taps will of course be required to be still below the cw storage tank as they will be more pressure required that is achieved between the cw tank and the hw cylinder. The two are directly related.
With regard to Ice's situation, if the hot water cylinder is moved to the attic, not raising the cw storage tank to a suitable height above the cylinder will result to having no hot water in any taps within the house. Downstairs hw water taps will achieve a greater pressure as they will have an additional head height between the outlet of the hw cylinder and their location.
Remember, the cw storage tank feeds the bottom of the hw cylinder and hw exits at the top, so a required pressure is needed to push the water through.
I have seen many cases where solar installations have been carried out and the hw water cylinder was changed from a 120 litre cylinder to a 300 litre cylinder (same diameter but much taller). The result was little or no pressure in the hot water taps. Especially when anti-scald valves are fitted as most of these valves require a minimum pressure to open and also an equal pressure between the hot and cold to balance.


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## ice (9 Jan 2011)

Shane007 said:


> Yes it would be a fairly substantial job. First you will need to decide on what size of hw cylinder you require. Then calculate the loading and see if your ceiling joists are large enough to carry this additional weight and of course is there enough height in the attic to site the cylinder. Secondly, be aware that you will require something like a 4 bar pump, which are pricey enough. Monsoon pumps are probably best and will cost in region of €400. You should also note that everything will be pressurized and when you flush a toilet the pump will run. Open any taps, the pump will run. Stainless steel cylinders with pressure kits are quite expensive too.
> If you can find an alternative, I would, such as move it else where on that floor.



It's staying where it is so ! 

Thanks for all your help guys


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## Leo (10 Jan 2011)

Shane007 said:


> Sorry, but Leo is absolutely correct.


 
Yey, I can come back out of hiding now


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## villa 1 (10 Jan 2011)

The hot water storage cylinder can be fitted in the attic area once the cold water storage cistern is fitted above same.
The pressure in the hot water taps below in created by the static pressure between the water level in the storage cistern and the hot water tap outlet(s) below.
The higher the cistern location in the attic space the greater the pressure below at both hot and cold outlets.


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## bstop (10 Jan 2011)

Exactly Villa1.
The critical design features are that the cylinder hot water tap off point should be below the cold water storage tank outlet and the expansion pipe must rise above the top of the storage tank.


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## ronny78 (10 Jan 2011)

Would this be a situation where a combi-boiler would be cheaper to install than the work associated with the cylinder re-location and potential problems? If the space was really vital to the renovation? Just a thought!


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## laoisfan (13 Jan 2011)

Could one's house insurance be affected by moving cylinder to the attic?


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## villa 1 (13 Jan 2011)

laoisfan said:


> Could one's house insurance be affected by moving cylinder to the attic?


 
 Would'nt think so, if the cylinder was installed, insulated and supported properly. Then again most house insurers these days are saying that your house either is sinking into the ground or is going to get swept away in a flood, just to increase premiums!!
A lot would depend on the relative experience of an assessor if there was a problem.


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## pache (15 Jan 2011)

One issue that could arise from moving the cylinder up into the attic,thus reducing the distance between the storage tank and the cylinder,is air could be drawn into the cylinder vent pipe when a hot tap is running and lead to an anoying senario where you could have air and water flowing out the tap at the same time.


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