Water enters my boiler at a certain ground temperature, for example 5 degrees, if it entered my boiler at a greater temperature, for example 10 degrees, would this mean I would use less gas to heat the water ? 
temperature
- Thread starter Scarletroger
- Start date
Depends on the boiler, its output and the temperature setting.
Most combi boilers are designed to raise the temperature by around 35 degrees. They will have a limit based on the temp controller.
Most combi boilers are designed to raise the temperature by around 35 degrees. They will have a limit based on the temp controller.
Thanks guys,
My next question is- if I ran a pipe from the point the mains enters my home up to the attic and back, and then re-join the boiler input, I would therefore increase my input water temperature, by a few degrees, and save gas. And therefore................
This means that if every house was to connect a vertical pipe up and back, and raise water temperature, each house would save gas, without using anymore power.
Even if across the country it was only a saving of 2-4 %, this would save the construction of power station.
Can anyone see a problem with this logic ?
My next question is- if I ran a pipe from the point the mains enters my home up to the attic and back, and then re-join the boiler input, I would therefore increase my input water temperature, by a few degrees, and save gas. And therefore................
This means that if every house was to connect a vertical pipe up and back, and raise water temperature, each house would save gas, without using anymore power.
Even if across the country it was only a saving of 2-4 %, this would save the construction of power station.
Can anyone see a problem with this logic ?
I'm afraid that's not going to work.
Presumably you hope that as the top of the house is generally warmer than the bottom, there is "free" heat to be picked up by the water. Don't forget this heat has generally got there from the boiler, and if you take it out of the air and into the cold mains water, the air will have to be heated again to make up the loss. The additional heat will most likely come from burning gas.
That's without even thinking of the mechanics and efficiency of heat transfer from the air to the water in the pipes.
You might be interested in looking up the Zenex gas saver. This works on a similar principal in that it uses surplus (but in this case waste) heat to pre-heat the domestic hot water.
Presumably you hope that as the top of the house is generally warmer than the bottom, there is "free" heat to be picked up by the water. Don't forget this heat has generally got there from the boiler, and if you take it out of the air and into the cold mains water, the air will have to be heated again to make up the loss. The additional heat will most likely come from burning gas.
That's without even thinking of the mechanics and efficiency of heat transfer from the air to the water in the pipes.
You might be interested in looking up the Zenex gas saver. This works on a similar principal in that it uses surplus (but in this case waste) heat to pre-heat the domestic hot water.
Thanks, I'm learning a lot, however I was basing it on the fact that all though the year, upstairs in our house is about 7 degrees warmer, due to the sun warming up the house, even without central heating on, than our upside down bedroom below, therefore, an exposed pipe near our ceiling would be at least 10 degrees warmer than the cold mains coming in, summer or winter. Also it could also be run through a solar-heater or even a conservatory/ glass porch.
Thanks.
Rog
Thanks.
Rog
The effect would last a few seconds.
You can't do this for every boiler. Not all boilers can accept preheated water.
I see where you're coming from, i think, but by the time the boiler has lit and started to heat the water you would use up all the 'warmed' water in the run of pipe before the boiler and then it's back to the cold water from the outside mains. Just like when you turn on the cold tap for a drink - if you drink water from the tap that is - it's a little warm so you run it for 30secs to have it cold, you're running the warmed water that's been stored in the pipe out to get to the cooler outside mains water.
You'd need hundreds of metres of pipe before the boiler and the time to leave it for it to rise in temperature by any useful margin to have enough for say what a combi heats for a shower. 1mtre of 22mm pipe holds approx 380ml of water (180ml for 15mm). A 10 minute shower can use anything from 8 - 15 gallons of hot water, depending on how hot you have it, shower head etc, that's 37 - 68 litres! The pipe suppliers would have a field day
You'd need hundreds of metres of pipe before the boiler and the time to leave it for it to rise in temperature by any useful margin to have enough for say what a combi heats for a shower. 1mtre of 22mm pipe holds approx 380ml of water (180ml for 15mm). A 10 minute shower can use anything from 8 - 15 gallons of hot water, depending on how hot you have it, shower head etc, that's 37 - 68 litres! The pipe suppliers would have a field day
Sorry guys, I think so far out of the box, I always think that there a solution.
What if, just before the boiler, you connected a mains pressure tank of 60 litres, which would stand at room temperature, approx. 15 degrees C, therefore this would adequately solve the quantity needed. This is ten degrees warmer than mains water, and would reduce gas usage. A ten percent reduction in my bill is about £120 a year, and pay for itself in one year.
Are there tanks available, this would be after your drinking water connection, but before the boiler, in fact most combi boilers have had their immersion tanks removed in this space.
What if, just before the boiler, you connected a mains pressure tank of 60 litres, which would stand at room temperature, approx. 15 degrees C, therefore this would adequately solve the quantity needed. This is ten degrees warmer than mains water, and would reduce gas usage. A ten percent reduction in my bill is about £120 a year, and pay for itself in one year.
Are there tanks available, this would be after your drinking water connection, but before the boiler, in fact most combi boilers have had their immersion tanks removed in this space.
You can't just bung any old tank on the mains feed to the boiler.
You'd have to use an unvented cylinder with its insulation stripped down. Even then it would take hours and hours for the water to reach entropy with the ambient temperature and minutes to cool again.
I wouldn't call this thinking outside the box.
You'd have to use an unvented cylinder with its insulation stripped down. Even then it would take hours and hours for the water to reach entropy with the ambient temperature and minutes to cool again.
I wouldn't call this thinking outside the box.
Ground-source pre-heat.
Drill a borehole vertically in the ground.
Use uninsulated pipe for the down part and pre-insulated pipe for the up part of the pipe.
Construct and fit a return bend for the pipe.
Run a mains feed for the boiler through the pipe/collector then to the DHW feed on the boiler.
Simples.
Drill a borehole vertically in the ground.
Use uninsulated pipe for the down part and pre-insulated pipe for the up part of the pipe.
Construct and fit a return bend for the pipe.
Run a mains feed for the boiler through the pipe/collector then to the DHW feed on the boiler.
Simples.
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