Domestic Hot Water Circulating Devices

File note - the Hot Water Lobster arrangement is not approved for use in UK water systems.

Hello PWSlack,

Can you please tell me why the Hot Water Lobster is not approved for use in UK water systems? Is there a backflow issue into the municipal water main?

BTW, I live in New York State, USA. I have a Watts Regulator double check valve installed on my cold water service line just down stream of the flowmeter & meter horn and the main interior shutoff. there's also a service curb stop box and valve located out at the Right-Of-Way Line.

Thanks!

In the UK, potable cold water has to be kept separate from potable and non-potable hot systems through the use of an air gap in order to comply with water byelaws. The Lobster arrangement does not achieve this, and therefore cannot be installed here.

I love the name though......hot water lobster

Personally, I`d put my hand in my pocket to pay for the 300 watts needed to get the hot stuff all around the house.

If the potable water location were isolated the lobster could also be used in the UK?

This is what we do, use a separate cold filtered line to the kitchen sink or other potable locations then use a lobster on the lines where ready hot water is beneficial. Yeper we have a filtered cold potable line and a separate cold drinking RO tap and another cold tap for general plus the hot tap at the kitchen sink. It's very simple with an auxilary filtered potable cold tap at the stove too.

Captain, you will be running a return pipe from your bathroom to the furnace. There has to be good vertical difference between the hot outlet and the cold return for the lobster or a natural thermo-syphon to work. Go ahead and plumb it in just as a thermo-syphon. If it works naturally, the lobster should work. If you get no flow, you will have to use the electric pump, which can be at the furnace, or anywhere in the line. I have a really cool one on my solar unit, it has a timer so it is off when I want, and a sensor to turn it off when the water is hot enough. The sensor can be at the sink .This is it. ThThe

T

I couldn't suggest either for your application because either will increase the demand upon the oil fired boiler.

On the other hand if you installed a variable input temperature point of use water heater that may be configured to operate at 120vac and only until the heated water from the boiler got there the overall efficiency would increase.

Taco and Grundfos both make fractional horsepower small, inexpensive, efficient 120v pumps.

....and come highly recommended <usual disclaimer>.

HELLO

You could try a solar driven DC pump from wsetech.com. Or Another pump you may be interested in is the bubble pump US Patent 5351488. I think there is a company called BAP limited <www.bubbleactionpumps.com> that manufactures them. It would be an interesting alternative as you are in a colder winter clime. Hope the info helps. I have no direct knowledge of either pump. I did have a company that installed traditional pumps like the Grundfos.

Hello Guys,

I appreciate all of the input, answers and solutions.

From the responses, I take it that the Hot Water Lobster will do me no good at all? It really wasn't fully explained why. I do have separate hot water and cold water supply lines serving all fixtures throughout the house (branched off from the both of the main lines which are 3/4-inch copper each), so I see no reason to add an additional return line back to the boiler (not a furnace as someone had inferred).

Just a little more info: I DO get hot water in the lines (after running the fixture for a few minutes) even when the boiler is NOT fired-up like it would be for heating the house via the Hydronic system. So, to me that means there must be enough heat generated by the pilot flame to provide sufficient hot water.

Anyhow, I am planning on installing my Solar Thermal System (to heat the house and provide DHW) in the spring, so there should be more than enough enough hot water generated from the thermal storage tank and heat exchangers where I think the Hot Water Lobster installation would be beneficial. I'm also trying to avoid wasting water by running the fixture taps or shower full tilt so as to get the hot water flow.

Like I said before, I want to stay away from recirculation by pumping the water if at all possible, but rely on convection instead. I need to keep down the energy cost around here as much as possible.

Have a Happy Thanksgiving guys!

Check Shahand's thread of 10/09/09 'Heating water for pool'. It got 120 replies, about thermo-siphon. The only way to have hot water readily at your tap is either to heat it there, or return the water back to the source when it is too cool. Insulate both lines.

I have a tankless hot water heater that serves 5 main runs, kitchen, master bath, bath, spa tub, and laundry. Some of the runs are long ~70', so getting hot water to the fixtures takes a while. I installed 3 Taco circulator pumps for the first 3 uses above, in the cabinets under the sinks. I did have to run power for the baths, but it was simple as there were outlets on the other side of the common walls, so I just located the stud space and fished wire through to the outlet to power a new outlet.

These pumps only operate when a manual switch is engaged and only run for a short time, circulating water from the hot supply back through the cold supply until a thermostat in the pump shuts it off when the inflow temperature setting is met. They were somewhat expensive, as it takes a high-flow pump to trigger the tankless heater to operate. With the system that you have, you could use smaller pumps. The energy consumption is minor and the advantage is significant, especially here in New Mexico where water is precious.

You should visit a good commercial plumbing supply for advice on a suitable pump and its requirements.

Friend,

Listen to the good advice here re return line. Think about it; if the cooled-off water (in the hot water line) at the tap has no place to go, how can you get hot water out of your tap other than by running the cold water out into your sink? The return line is required, either for a pump or for convection flow.

The return pipe should NOT be insulated. The heat "lost" from the return pipe goes to heat your house so it really isn't lost. Especially the last ten feet or so should be uninsulated copper pipe to provide the necessary heat loss to get the water moving. Install a check valve just before the copper pipe goes into the water heater. Of course, the water heater must be lowest component in the whole sytem in order to work.

Since you indicated you were re-configuring your hot water system with solar heat, you will likely be moving components and plumbing anyway. So this is the perfect time to set yourself up with a convection loop.

and perhaps a swing check valve for convection returns to hw, horizontally