recirculating hot water?

jonny88

hi ,we used to use bronze circulating pumps on our return lines on our potable hot water.these pumps would run constantly.lately we havent been using them,our boss thinks they are to expensive.even in my house i have an oil boiler with a storage tank and a 006 bronze pump running constantly betweentank and boiler.i suppose my ? is ,is there a more economical way to circulate your hot water is does it not cost much if pump is running continously.thanks.

Steamhead

Your boss will find out

how inexpensive bronze pumps are, when he has to replace a bunch of iron ones under warranty and deal with angry customers. 

Charlie from wmass

pump should be

controlled by an aquastat. why run it constantly? I use an aquastat on the domestic tank to conrtrol the pump other wise you are using the boiler as a radiator for the chimney and the tank as a heat source as soon as the tank reaches temp and the burner cuts out on temp for the boiler.

jonny88

re circ line

in apartment buildings we always use the bronze pump so when tenneant opens faucet they dont have to wait 10 mins for hot water,ok.now in a house i think the code says if furthest fixture is not more than 100 feet away from tank no means of circulation is necessary,that looks like a lot of water to waste to me to wait for hot water.steamhead we sometimes dont use pumps in these situations,he calls it a gravity return,we pipe it into the bottom of water heater with a check valve.is a pump necessary,thanks for your input guys,hope ye are keeping busy

Mark Eatherton

There is no such thing as gravity...

The Earth sucks, and that is what keeps us on its face :-) (told to me by my 10th grade science teacher in high school)



Yes, gravity CAN work, provided that all distribution is above the tank, and there are no thermal traps.



I've done this before, using a venturi fitting where the return comes back into the cold water main serving the DHW system. The venturi "enhances" the gravity effect, and keeps the hot water rising and cold water falling.



I've never used a swing check. Instead, I will take a nickel ($0.05) and drill a 1/8" hole through it, place it in the side branch of the circulation return/cold water main connection, and hold it in place with the 3/4" copper tubing. Make sure you mark it as such or some poor unsuspecting technician is going to be pulling his hair out trying to figure out what's going on.



As for wasting water, at present, water is cheaper than energy, and if there is a circulation return, there will be wasted energy radiating from the mains and the circulation return line.



When water gets as expensive as gasoline, maybe attitudes will change, but for the present time, it is what it is...



Another little trick for those that do incorporate circ returns into their system. Keep the hot water main and circulation return lines in completely separate joist bays to avoid the "We can NEVER get cold water" syndrome. It's not going to cost you a lot more to do it that way, and the consumer WILL be able to get a drink of cold water from any tap in the house.



ME

Charlie from wmass

Ok I was understanding this

was a storage tank with a tankless coil. Still aquastat applies though. it does not even have to be set all that high. Dad likes using gravity as he says it does not shut off. the issue is though if the pipes are not insulated that's lots of heat to waste because it does not shut off. of course one could use an aquastat and a solenoid valve rated for domestic water.

jonny88

sorry charlie

i just threw that in as in my system at home which is getting ripped out soon the circ continuosly runs eventhough there is an aquastat on storage tank.im not familiar with oil systems .hot water comes out of coil i and circ from what i see circulates from tank to coil.when i open a faucet upstairs i wait for hot water.i just added that as an example of continuosly running pumps sorry for the confusion.it is probably not wired right or something as there is a schematic which installer didnt follow,but as i said it is coming out soon.do you like the burnham mpo-iq or would you swutch to gas????????

jonny88

nickel?

where does the ideas like this come from.my god out of ignorance and unwilligness to learn my boss would throw it at me.but that is why we come here,to learn from the best,by the way im looking forward to taking dans class in hydronics in ny soon,maybe i will mention the nickel trick to him see what he says

Charlie from wmass

I have heard good things about the MPO

I am just now warming up to Burham. Mostly due to the Mega steam. Steamhead is much more familiar with the MPO than I am. I am starting to like gas more as each year passes. There are three pass boilers that can be converted to gas burners. I am not sure if the MPO is one. The trio from FWWebb can be fired on gas with the proper burner. How many BTU's are we talking for a boiler?

jonny88

mpo

i havent done a heat loss calculation yet,im going to look at a contractor here to see if they can do it,im not 100%confident yet and my supply house takes an easy way out .i got a 93 year old grandma downstairs so i would love for her to be comfortable,she turned of her heat a week ago........i seen steamhead does consulting work ,i might try and contact him and see what he thinks of some of the ideas i have,again thanks all for your help

STEVEusaPA

has anyone ever tried....

I was just wondering if anyone has ever tried wiring the circ, with an aquastat, that's tripped on by a flow switch on the outlet side of the indirect, and shut off by the aquastat measuring temperature on the returning circ line?  I've seen the systems with sensors on each room (wired/wireless) that someone pushes a button to turn on the, then the circ shuts off automatically via a return temperature sensor.  But instead of all the extra wiring, I'm thinking why not turn the circ on only as needed.  My guess is it only needs to run less then a minute.  Any thoughts from people way smarter then me would be appreciated (and a sketch )  Thanks.

Charlie from wmass

Well since the people smarter than you seem to be busy I'll give it a shot.

by the time you have flow you are already wasting water. that is why some places have the button. you hit it before you need the hot water. I like the use of gravity because as the return water gets warmer it naturally slows down as the density of the water gets to be closer and closer to the water leaving the tank. It never quite gets to the same as it cools to the environment along the length of the pipe. I recommend insulating all hot water and recirculation lines.

Ron Jr._3

One way to save some electric

is to use a timer for the circ . I bought a cheap, plug in timer for my sister's recirc line ( less than $20 ) . It has pegs to turn the 006 bronze circ on and off 4 times a day . It's wired in with an aquastat set 10 degrees lower than the indirect's setting . After 5 years and with electric around  $ .22 a kilowatt hour , it paid for itself and the aquastat many times over .  

tim smith

Re: Recirc etc

Johnny, I am not sure why you have the pump running constant between the boiler and the water tank? that is a waste of electricity and thermal loss too. Regarding recirc pumps, we only use stainless fitted or Bronze pumps. Smaller the better. In my house, i have a occupancy sensor in our main master bath, as soon as I walk to the door, the recirc kicks on and hot water is at tap in ~15 sec. or so. I oversized my recirc a little for this to  get it there faster as normally on constant circ we go with smallest pump that will work to limit pipe erosion. The occupancy is my favorite method as it limits energy loss from piping and also electric useage.  Good luck, Tim

jonny88

thanks tim.

im getting my friend to look at the wiring on my boiler and eliminate the need for the pump to run constantly,when our customers want recirc pumps we do go with taco stainless or bronze.thanks for your info i like the souns of kicking the pump on with a switch,

icesailor

Another way:

Anything will work.

This is what I do when I can.

Recirculate to the farthest fixture or to the one in the Master Bath. Aquastat to turn off the circulator pump when the return gets to the set temperature. A digital time clock to act as a "fake" clock thermostat. If the residents get up at 6:00AM, I have the clock turn on the circulator at 5:45 AM and turn it off whenever. I have it come back whenever they want it. I let them set the parameters. I then use a five minute light timer that you use in a bathroom for a heat lamp in the ceiling. If the system is off at midnight and someone wants hot water without wasting it, turn the timer as far as it will go. The circulator will start and no water is wasted. It gets hot in a few. The owner will know how long it takes. When they are done with the water, the circulator will have already stopped. If you get a quality clock, it has a 9 volt battery back up.

Every customer I have rigged up like this has been extremely happy.

Every recirculation line should have an open on rise controller on it. It shouldn't be left to just run constantly. That's wasteful.