Water to water side arm

[Holmes]

Side arms are not based on volume capacity. They are based on surface area heat transfer, with water flowing thru separated areas. Circulators increase the amount of flow thru the heat exchangers. Evan a small unit working by gravity feed will help save $ on making water hot.
The flat plate exchangers have a larger surface area inside them, they are built like a sandwich with 10, 15, 20, 30 or more layers.

[Slabs]

 

 

Here's one end of my "side arm" heat exchanger.  It consists of two ten-foot pieces of 3/4 inch copper pipe inside two ten-foot pieces of 1 1/2 inch pipe.  The ten foot  lengths were to accomodate a 14 foot wide basement.  The boiler return pipe is shown entering and exiting the side arm.

[woodmills1]

my side arm has heated my house water so well that PSNH(new hampsire public service electric) threatened to charge me with turning my meter upside down

took two years to convince them not to prossecute

my electric bill goes down 40 bucks a month each heating season

the electric only gets used to heat when a bath and a shower and a load of clothes are done in succession


and the water is so hot I needed a tempering valve to keep my skin

[thecfarm]

My hot water tank is basically a place to store my hot water. I turn the switch off. And that is with a side arm.

[NWP]

I shut the breaker to my water heater off when the OWB is running.  Reason is, I figure if I forget to fill the stove and the water temp in that system gets too low the water heater will start working in reverse trying to heat the OWB water.

[Logging logginglogging]

Side arms are not based on volume capacity. They are based on surface area heat transfer, with water flowing thru separated areas. Circulators increase the amount of flow thru the heat exchangers. Evan a small unit working by gravity feed will help save $ on making water hot.
The flat plate exchangers have a larger surface area inside them, they are built like a sandwich with 10, 15, 20, 30 or more layers.

I dident know about the layers... This makes since if it has to flow through all layers. But it seems like the water would not spend very long and heat very much in the tube style ones. it just flows right through.

I am definatly gonna do a side arm, but I am leaning towards the Plate type now.

[r.man]

The tube style heaters work fine. They do have to be installed properly, within a foot or so of the water heater and care has to be taken that cold water can't pass through them to get to the hot water outlet. They will overheat your water so a mixing valve is a good idea if you have small children in the house but we like the extrahot water for doing dishes and warming up a cooling bath. Our electric hot water heater has the breaker turned off while the furnace is fired. If I had a young family I would install a 60 gallon or two 40s. One advantage of the second tank is that it doesn't have to heat in the off season, it just can't leak.

[forest]

I used a side arm for years and lived with a slow recovery rate for hot water. For some reason it was also necessary to turn off the valves to the side arm if I required lots of hot water, otherwise I would get some hot water, then lots of warm water. I went to a different system last year and it has worked great. It uses a plate exchanger and a pump which is run by a temperature gague inserted into the tank. I have turned off the electicity as long as the OWB is running. I have achieved almost instant hot water with this system. forest

[Logging logginglogging]

I used a side arm for years and lived with a slow recovery rate for hot water. For some reason it was also necessary to turn off the valves to the side arm if I required lots of hot water, otherwise I would get some hot water, then lots of warm water. I went to a different system last year and it has worked great. It uses a plate exchanger and a pump which is run by a temperature gague inserted into the tank. I have turned off the electicity as long as the OWB is running. I have achieved almost instant hot water with this system. forest

That sounds good.
Do you have a link or pictures of this setup?

[r.man]

Forest, a sidearm should work without adjustment during use. They are sensitive to being piped right and I know of a few that had to be repiped because there was cold water flow through the sidearm. The best way I have seen to do it is to remove the drain pipe, tee and reinstall the drain tap, pipe the bottom of the sidearm into that and pipe the top into the pressure relief hole with a tee to allow the pressure relief to be reinstalled. This will keep the cold water flow far enough away from the sidearm to eliminate problems. The main problem with a plain sidearm is that the water can be very hot.

[forest]

The plate water to water exchanger hooks into the cold water intake to the tank and the hot water outlet from the tank. The hot water to the house and the cold water from the line are above this line. Both the intake and outlet are on the top of the tank. The pump draws from the cold inlet and returns to the hot. The success of the system is the efficiency of the hot water exchanger. The water from the stove comes in on the bottom and out on the top and reversed for the lines coming from the tank. The copper pipe inlet from the stove can be too hot to touch while the outlet is cool having given up its heat to the water in the tank and some to the room. This happens as long as the pump is circulating water. It takes between five to ten minuets to bring the temp to the tank up sufficiently to turn off the pump. It is a forty gallon tank. If you are taking off water when the pump is circulating the water is hot for as long as you need. That is why I say instant hot water. The exchanger was expensive but I sure have been happy with it.

[r.man]

Forest you might have a demand system with that plate to plate if it is as good as you think. How much was " expensive " or can you provide me with a link to the manufacturer? Thanks. How's the weather in Kenora? Was -18 C, 0 F last night, I think that is the coldest yet this year.

[firechief]

I have the same side arm that Draco describes from Central Boiler.  Does a great job going on heating season 4.

I have a family of 5 and our water heater is not even plugged in or turned on.  Have not had any issues with running low on hot water.

[Corley5]

  If your water has a high calcium content the heat changers whether tube sidearm and plate will plug.  I had a flat plate one that plugged solid the first season.  My parents had a tube sidearm that plugged within three seasons.  The guy that installed my parents system also had trouble with lime scale.  I've got a tube and shell exchanger waiting to be installed on my new system.  It can be disassembled for cleaning.  To control the potable water temperature I use a strap on aquastat to turn the circulators on and off.