ChatterBank1 min ago
How to Raise Water Pressure without an electric pump?
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We have solar hot water heater system, but the main tank is on the same floor as the rooms it serves. There is not enough hot water pressure to mix with the cold water for a nice shower. How to increase the water pressure without an electric pump?
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We have been looking for a 28v DC circulation pump that makes no noise, but so far, have not found any source. Our building is extremely quiet and so we have to be certain that an electric pump makes no noise. Any suggestions for suppliers?
Raising the tank is a possibility, but not so desirable. It is 3000 litres capacity and will require opening a large hole in the pitched roof.
However, we are wondering, if we raise the small feeder tank which contains the regulating "float valve" (like a toilet valve) that controls water supply to the main tank will the pressure increase? This small feeder tank only holds about 100 litres. But it would be much easier to put that tank or a slightly larger version of that tank on the roof top and just poke a couple holes in the roof for the pipes. Any comments about this option? Would it raise pressure significantly? The top floor, has 12 rooms that want shower pressure hot water.
Raising the tank is a possibility, but not so desirable. It is 3000 litres capacity and will require opening a large hole in the pitched roof.
However, we are wondering, if we raise the small feeder tank which contains the regulating "float valve" (like a toilet valve) that controls water supply to the main tank will the pressure increase? This small feeder tank only holds about 100 litres. But it would be much easier to put that tank or a slightly larger version of that tank on the roof top and just poke a couple holes in the roof for the pipes. Any comments about this option? Would it raise pressure significantly? The top floor, has 12 rooms that want shower pressure hot water.
putting 3 tonnes of water in the loft/on the roof may cause bigger problems than just opening a large hole in the pitched roof!
Increasing the height of the header tank will increase the pressure from the header tank to the main tank but not the pressure from the main tank to the showers (unless it's a totally sealed system, and then it would only be a small increase)
somebody else may be able to offer a better idea (I think theBuilder and ALbags have both installed solar systems) but I think a pump is your only realistic option
(and 12 rooms on the top floor!!! do you live in a hotel?)
Increasing the height of the header tank will increase the pressure from the header tank to the main tank but not the pressure from the main tank to the showers (unless it's a totally sealed system, and then it would only be a small increase)
somebody else may be able to offer a better idea (I think theBuilder and ALbags have both installed solar systems) but I think a pump is your only realistic option
(and 12 rooms on the top floor!!! do you live in a hotel?)
First off, Monk ............ I guess
1 the hot water feed is a gravity system
2 the cold water feed is mains pressure?
If that's right, instead of raising the hot pressure, try reducing the cold pressure so that they match (approx). As you've discovered, even thermostatic shower valves like to have a "balance" between H and C supplies.
You could fiddle with pressure regulators etc in the incoming main, but it's difficult, as you tend to get reduced FLOW rates then. i.e. the cold pressure is right, but the AMOUNT of water available is reduced.
A good solution would be to take a low pressure cold feed from your header tank (just like the one that goes to the hot storage tank. You'll then have H and C feeds at the same pressure.
Any of that making sense? :o)
1 the hot water feed is a gravity system
2 the cold water feed is mains pressure?
If that's right, instead of raising the hot pressure, try reducing the cold pressure so that they match (approx). As you've discovered, even thermostatic shower valves like to have a "balance" between H and C supplies.
You could fiddle with pressure regulators etc in the incoming main, but it's difficult, as you tend to get reduced FLOW rates then. i.e. the cold pressure is right, but the AMOUNT of water available is reduced.
A good solution would be to take a low pressure cold feed from your header tank (just like the one that goes to the hot storage tank. You'll then have H and C feeds at the same pressure.
Any of that making sense? :o)
I'm not sure we have a closed system or open system for the header tank, Here are more details:
The small header tank is gravity fed, both incoming and outgoing, and has an open top and rarely overflows. Overflow of the header tank occurs when somebody "backflushes" the hot water system from their room, (by opening the cold water feed to their supplemental electric water heater in their room).
The supply pipe to the rooms for the solar heated water is 1 inch, but the pipe going into each bathroom is 1/2 inch. The cold water supply to each bathroom is a 1/2 inch pipe.
The main cold water feed comes down the mountain in a 3 inch pipe. To reduce pressure from this feed, an intermediate tank was located up the hill from our facility. It is a simple concrete tank that allows water to overflow the top when full (but most of the overflow it is piped away for other uses). The solar hot water tank is located on the top floor of our facility (3 floors, 36 rooms total). The platform for the hot water tank is reinforced with strong steel I-beams and would be used for a base to raise the tank above the roof.
Perhaps a fundamental question is: if height = pressure, does weight of the water (volume) also = pressure?
That is, if the header tank holds 200 litres, will it provide more pressure than a header tank holding 100 litres?
We are not familiar with pressure regulators. The pressure of the cold water feed is at a desired level.
All of your suggestions and comments are much appreciated.
The small header tank is gravity fed, both incoming and outgoing, and has an open top and rarely overflows. Overflow of the header tank occurs when somebody "backflushes" the hot water system from their room, (by opening the cold water feed to their supplemental electric water heater in their room).
The supply pipe to the rooms for the solar heated water is 1 inch, but the pipe going into each bathroom is 1/2 inch. The cold water supply to each bathroom is a 1/2 inch pipe.
The main cold water feed comes down the mountain in a 3 inch pipe. To reduce pressure from this feed, an intermediate tank was located up the hill from our facility. It is a simple concrete tank that allows water to overflow the top when full (but most of the overflow it is piped away for other uses). The solar hot water tank is located on the top floor of our facility (3 floors, 36 rooms total). The platform for the hot water tank is reinforced with strong steel I-beams and would be used for a base to raise the tank above the roof.
Perhaps a fundamental question is: if height = pressure, does weight of the water (volume) also = pressure?
That is, if the header tank holds 200 litres, will it provide more pressure than a header tank holding 100 litres?
We are not familiar with pressure regulators. The pressure of the cold water feed is at a desired level.
All of your suggestions and comments are much appreciated.
It is really the wrong sort of hot water system. Solar hot water works best with high pressure storage tanks. The hot water floats on the sold water so the water supplied to the outlets is always a hot as can be available.
One solution would be a heat exchanger hot water storage tank. This stores the hot water at low pressure and has a coil of high pressure pipe inside. The high pressure cold water is fed into the coil where it is heated by the stored water by conduction then continues on to the hot water tap.
Are you sure the existing tank is not already one of these and has been wrongly installed? Unfortunately retrofitting a coil to the existing tank is probably not practical.
Raising the header tank would increase the pressure. However the storage tank and/or the solar panel may not be rated to cope with this extra pressure.
The electric circulation pumps develop very little pressure. Might be enough to make it work but you would need to check the pump ratings. One pound per square inch is the equivalent of two feet water height.
You could use an external heat exchanger. This has one copper pipe inside another larger pipe. The circulating pump moves hot water through the outer pipe while the high pressure water flows in the opposite direction through the inner pipe.
One solution would be a heat exchanger hot water storage tank. This stores the hot water at low pressure and has a coil of high pressure pipe inside. The high pressure cold water is fed into the coil where it is heated by the stored water by conduction then continues on to the hot water tap.
Are you sure the existing tank is not already one of these and has been wrongly installed? Unfortunately retrofitting a coil to the existing tank is probably not practical.
Raising the header tank would increase the pressure. However the storage tank and/or the solar panel may not be rated to cope with this extra pressure.
The electric circulation pumps develop very little pressure. Might be enough to make it work but you would need to check the pump ratings. One pound per square inch is the equivalent of two feet water height.
You could use an external heat exchanger. This has one copper pipe inside another larger pipe. The circulating pump moves hot water through the outer pipe while the high pressure water flows in the opposite direction through the inner pipe.
The heat exchanger idea is interesting. It would seem to solve all the main issues including pressure, maintenance, silent operation and installation. In fact, the heat exchange principle is used to heat the water in the main tank. There is a pipe structure in the main tank which is only connected to the solar panels - and it works very well.
One question: If the main water feed comes in 1 inch pipe, do we need an exchange structure that is also in 1 inch pipe, or could it be stepped down to 1/2 pipe inside the tank, then put back into 1 inch pipe going to the rooms? What would be the issues to consider? Presumably, we would use copper pipe inside the tank.
The calculation details regarding circulation pump requirements is much appreciated.
One question: If the main water feed comes in 1 inch pipe, do we need an exchange structure that is also in 1 inch pipe, or could it be stepped down to 1/2 pipe inside the tank, then put back into 1 inch pipe going to the rooms? What would be the issues to consider? Presumably, we would use copper pipe inside the tank.
The calculation details regarding circulation pump requirements is much appreciated.
If you could get the heat exchange pipe into the main hot water tank it would be great. However it is unlikely that it would be practical. I expect you would need an external one
In any case the cold flow through the exchanger should be fed from the bottom and outletted at the top. With the external one the hot should be from the top to the bottom.
As you seem to have plenty of pressure you should be able to change to a smaller pipe through the exchanger or tank. This would increase the surface area to cross-section of the heat exchanger.
The external one would need to be very well insulated as it is much smaller than the main tank so has a large surface area to volume ratio.
One possibility would be to mount a heat exchanger type mains pressure hotwater system slightly above the main tank. Pipes would connect the top of the two tanks and the bottom of the two tanks. These pipes would need to be as large and short as practical.
Hot water should convect from the large to the small tank where it could interact with the exchange coil. If this didn't hapen fast enough a pump could be used to circulate the hot water. One again I can't stress too much how that small tank should be very well insulated.
In any case the cold flow through the exchanger should be fed from the bottom and outletted at the top. With the external one the hot should be from the top to the bottom.
As you seem to have plenty of pressure you should be able to change to a smaller pipe through the exchanger or tank. This would increase the surface area to cross-section of the heat exchanger.
The external one would need to be very well insulated as it is much smaller than the main tank so has a large surface area to volume ratio.
One possibility would be to mount a heat exchanger type mains pressure hotwater system slightly above the main tank. Pipes would connect the top of the two tanks and the bottom of the two tanks. These pipes would need to be as large and short as practical.
Hot water should convect from the large to the small tank where it could interact with the exchange coil. If this didn't hapen fast enough a pump could be used to circulate the hot water. One again I can't stress too much how that small tank should be very well insulated.
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