Automatic Hot Water Recirculating Pump?...

[Batpig]

Dear Plumbers, Plumbing-Types, and Eco-Addicts (that means you Smurf :wink:)...

I wonder if any of you have either seen or heard of some type of on-demand, but fully automatic, Hot Water Recirculating Pump - sort of like a "Chilli Pepper" or a "Water Guardian", except that you don't have to press a button to pump the cold water in your hot water line back to the tank, because it's all done automatically as soon as the thing senses the start of any flow in the hot water line. Then, like the others, when line temperature reaches a certain higher level, it then stops pumping and opens the valve that permits hot water supply into the house.

Such a device makes too much sense to not eventually kill off units like the Chilli Pepper, because you might be standing in the shower in your Birthday Suit one day before you remember that the button for the recirculator is out on the Kitchen wall, above the sink...

Many Thanks,
Batpig.

[juan]

You mentioned earlier u had a 30m run of hot water pipe to heat. Is the aim of this device to save water? It surely will save no energy as it still has to heat the pipes.

Let the shower run into a bucket and use it on the garden if water is the issue.

[Batpig]

Dear Juan,

Even without a recirculating pump, and just having a bucket in the shower (which is what I do now), I don't think you would save an appreciable amount of energy because the object of the recirculating pump - like the "Bucket System" - would still be to only heat the hot water feed line up to the point of entry into the house - not all the way back around to the storage tank. The main difference would be that towards the end of the heating-up process, water just below the switch-over threshold temperature would then be heating up the return line back to the tank in the recirculating pump scenario, rather than the internal hot-water pipeline inside the house in the bucket scenario. Since the pipe run outside the dwelling in question is substantially longer than the pipe run inside, the water savings to be made with the recirculating pump would most probably outweigh the energy savings to be made using the Bucket System. And remember too, it also takes energy back at the water treatment plant to purify the stuff before they pump it down the line to us.

I can see your point, though.

But back to topic: has anyone seen one of these rare birds that I'm chasing?

Many Thanks,
Batpig.

[Barry_White]

Batpig

Rheem used to have recirculating pump that they used to have attached to their mains pressure solar hot water system that used to recirculate the water from the ground standing tank up to the solar panels to heat the water.

This pump was designed to turn on if the water temperature in the solar panels dropped below 4 degrees C. This was to circulate the water of a night time to prevent the water in the solar panels from freezing and damaging the solar panels.

The problem was that the pump couldn't pump sufficient water to circulate when the temperature dropped down to -9 degrees C.

I did away with the Rheem tank and installed a Breamar gravity tank and converted the solar panels to the thermo-siphon system and sold the Rheem tank pump and all.

I don't know if Rheem have this in their current model but possibly they sell it aa a spare part.

I think it would be an ideal solution to your problem.

[davo2310]

did you mean something like this


http://www.ecosmart.com.au/water_guardian.html

[Barry_White]

Another thing you could look at is a solar heated pool setup that has sensors for both the solar panels as well as the pool incorporated in a pump.

[Batpig]

Thanks Barry - it does sound good, but I didn't want it to actually run at any time that the water dropped below a certain temperature in the hot water pipe, but instead only when a water flow in the pipe occurred (due to an opened tap), and the pipe temperature was also below a certain threshold level...

Davo - very similar to that, but instead of needing a button to be pressed for activation, the whole thing was instead activated by an initial flow of water through the line due to an opened hot water tap. Once the flow was detected, the water temperature was quickly measured, and if it was below a certain level, a valve closed off flow to the tap, and a pump kicked in to keep sending the water currently in the pipe back to the storage tank until the water in the pipe had reached the threshold temperature. In other words, like a Water Guardian, but activated by a detected initial water flow rather than a pressed button.

Thanks all the same,
Batpig.

[tricky4000]

Hi guys,
I'm new to this and I'd like to say I'm very happy to have found this forum. I look forward to learning new things, as I have in the past from this site. Thank you for all the input and I hope I can help someone out one day too.

I have one of these systems in question at home. Its called a Rinnai Smart Start pump and it attaches itself to a Rinnai Infinity 26 Plus instant HW heater.

When you press the Preheat button on one of the controllers, it activates the pump and heater and pushes HW to the furthest tap in the HW pipe network and brings it back to the heating unit. When you open a tap, hot water is ready to go...maybe a little cold water in the short pipe run though to the tap though.

If I don't use this pump, I waste about 10 litres of cold water in the kitchen...and this is a small house! I'd hate to see what would be lost if it were a double story 40 sq home with the HW heater on a 3/4" pipe diameter x 20m run. :)

Dan.

[silentC]

They do use electricity though. If you're on mains, there's another solution to that problem that doesn't. It's a valve that detects a drop in pressure when a hot tap is turned on. That opens the valve which diverts the cold water from the line to a bladder or into a rainwater tank. Then when the water gets to the correct temp, the valve closes again and the water goes to your hot tap. There's a bit of a delay while you wait for water to come out but it's no different to pressing a button and waiting. They're about $200.

They work if you're on tank water too, but you don't really gain anything electricity-wise over the pump systems because you are still running your pump to bring cold water into the HWS.

[Batpig]

Dear Silent,

Doesn't quite sound like what I'm looking for, but I'd sure as heck be interested in having a look at it, though... Any idea of the manufacturer's name?

Thanks,
Batpig.

[silentC]

Here is his web site: http://www.enviro.net.au/savewater.html

The way I used mine is I put the valve right up under the floor beneath the kitchen sink. The divert line is a bit of poly pipe that runs to a downpipe near by. When I turn the hot tap on, you can hear it running. It takes a minute to clear all the cold water from the line and then the hot comes through. We're on tank water, so the cold just goes back to the tank.

I don't think it's possible to set it up as a ring main because the pressure in the line would balance out and so no water would flow when you open the valve.

[Batpig]

Maybe not Silent,

But the valve could be sort of along the lines of what I'm looking for in this other thread:
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=68798

Can you tell whether the valve is electric, or simply passive?...

Thanks Again,
Batpig.

[silentC]

I'll reply in that thread...

[Plastic Fang]

Hi Batpig. I saw a device like the one you mention on the New Inventor program some months ago (check their website for details). Another alternative, which we did because our ensuite ans the main bathroom were at opposite ends of the house, was to install 2 x Rinnai Infinity 26's - one at each of the house to avoid pumping hot water over long distances.

[Batpig]

Dear Plastic,

I think that must be the same unit that Silent is talking about. Good idea using the two Rinnai's though - would a pair of 16's have been any cheaper than the two 26's?

Best Wishes,
Batpig

[bricks]

You need a Hot water return line installed, the set up you are describing is much to complicated to install for a decent price.

Hot water return lines keep water flowing around your pipes slowwly all day long, if the temp drops too far the heater kicks in. Because the hws turns on at a higher temp it actually does less work than a regular heater and thus saves energy.