Long, long, header- circ placement question

Brad White

I am thinking a small "jockey" circulator operating off of a local aquastat may work. This will "pull" water from the supply and would shut off when the return reaches temperature.

I would strongly advise that the pipe mains be well-insulated as this will be a parasitic heat loss. Heat when you do not need it is wasted.

The flow rate need not be much, just enough so that you get hot water faster when it calls, if I get your situation correctly. A Taco 005 or a Grundfos 15-58 on speed 1 will move a good bit of water in a large pipe. Call it temperature maintenance.

Maybe I do not see the entire picture, but that is something that comes to mind.

On larger commercial and institutional systems (where the main pumps run whenever the OD temperature is below say 60F, I usually use a 3-way control valve or a bypass balancing valve on the more remote reaches. This would be for example a vestibule heater where constant flow to avoid freezing is advisable. But the primary reason is that this assures that the lines are "ready to go" and do not have to wait for a long run of water to be displaced when heat is needed. Much faster response. Just another idea.

Brad

Saggs

Got a friend with a small grocery store in town. Large 400K btu peerless oil boiler with hot water feeds a couple large Modines upstairs, a hot water coil and some baseboard. There are 3 zones piped off the near boiler piping with all circs pumping away. These work fine. Problem is: 11/2" black supply and return then leaves boiler room and heads to front of the store(in basement) goes 60 feet where there are 2 more modines and the baseboard with circs also pumping away. When baseboard calls for heat, it never gets the hot water to the end of the "header" until the large modine calls which is upstream of it. All these units dump into a common return line which is of the same length and diameter as the supply piping. The supply and return are not connected at the end and this is what I'm thinking needs to be done. Tie the two together and put a "common" circ on that pushes or pulls the water out to the farther reaches of this"header". Question is where to put the circ and what size? There is a spot to put it on the supply b4 it leaves the boiler room now if this works? There is about 200K btu's of load out at the far end of the piping if that helps. Thx sorry for the long story.

Saggs

Thx for the response Brad. I was going to run the "jockey" pump of an isolated end switch on a taco relay panel, so when any of the 4 remote zones call then the pump starts. Insulation is definately a must! Will the taco 005 circ move the required gpms from all the zones at that end? Talkin maybe 175-200k btu's? Will it matter whether it's "pushing" the water to the remote zones or "pulling" it back thru the return?

Brad White

All you really need to do

is to get the main piping to temperature so that your local zone circulator can take over and deliver water immediately to the zone radiation. So long as the circulator is downstream of the expansion tank connection, it does not matter regarding push versus pull. The head loss will not be much, maybe 2.0 GPM in all of that pipe may only be a few feet of head if that. Without a piping diagram and lengths with sizes, I am just guessing here, to be honest.

hot_rod

If you tie

the S&R together at the end you have built a primary loop, so to speak. then you would need a circ on every load, tied in via closely spaced tees.

I'm not sure you want to do that??

Keep in mind the temperature in the loop will drop at every "load" it sees. If I understand your piping arrangement. If one circ supplies both unit heaters and some baseboard, you need to determine the amount of GPM need to drive all those loads. You may just need some more circ capacity. The circ needs to move the combined gpm of all the loads, if they can all run at the same time.

A drawing would be great.

hot rod