Hot water loop

surfsup

Hi, I have a hot water loop coming off my steam boiler that is used for the downstairs heat, it's on a seperate thermostat. I bled the hot water zone and everything worked fine for a few days. One day i got home from work and the steam was pumping but my thermostat was on 64. I have since figured out that every few days to a week the downstairs zone stops working and if my tenant turns his thermostat up to  70 the steam pumps up stairs until the downstairs thermostat is satisfied. When the down stairs zone works everything is fine. Why do I have to keep bleeding my hot water loop so often? I have a TACO 007 circ pump fyi. Thanks in advance

Jason Quinn

Pics would help....

If you can post a few pictures of the system it would be helpful. Start with several pics and angles of the near boiler piping of the hot water zone. How are you bleeding the system? You shouldn't have air vents on this hot water zone. Perhaps there is an issue with the control wiring as well causing the boiler to steam when only the hot water zone is calling for heat. Calling a pro may be your best bet here.

surfsup

hot water loop

I have an aquastat set to 180 on the supply side. when I bleed the zone I shut the ball valve on the return and open the valve ahead of it till i feel the hot water then open the ball valve and shut the other valve. That does the trick for a few days and then its like ground hog day. Like I said everything works fine untill I lose the downstairs zone.

surfsup

hot water loop

surfsup

hot water loop

Jason Quinn

Circulation

Ok, so you're not getting any circulation thru the hot water zone. Is the pump working? Is it turning on when the thermostat calls for heat? Is the aquastat wired to the burner? Still not sure why the boiler steams until the downstairs "hot water zone" thermostat is satisfied.

surfsup

circulation

My problem is that I'm loosing circulation often. The aquastat is wired to the zone control. My thinking is that I'm loosing circulation to the hot water zone so how would the pipe ever reach 180 to trigger the aquasta to shut the boiler? In the mean time its firing away pumping steam up stairs until the therm which is only a few feet from the boiler is satified. I don't think it's a wiring problem but I could be wrong. But, what would make the hot water loop loose circulation so often? Thanks

Jason Quinn

Is the hot water loop

completely filled with water? Do you have valves and hose cocks on the supply and return to be able to fill the system and purge the air out of the loop? Is the pump working and turning on when the thermostat calls for heat? Is the loop system water dirty and the pump plugged? Is it a bronze pump?

surfsup

circulation

I would think it is completely filled with water but how would tell? I have a ball valve and hose cock only on the return side. yes the pump is working. I thought that particles were clogging the pump so I installed a Y screen. No, It's not a bronze pump. Would a bronze pump be better?

Charlie from wmass

the zone is piped wrong

there needs to be a way to prevent the circulator from cavitating when the water is boiling for steam. The circ needs to pump away from the boiler and have a bypass from the return to the feed between the boiler and the circ to temper the water below boiling entering the pump. also for that zone a BG 100 bronze would be the pump of choice because you are pumping on an open system not a closed one.

Jason Quinn

Surf

Charlie could be right. Your near boiler hot water zone piping could be wrong. Need pics to verify.

surfsup

pics

Thanks for the help guys!

Circulator and Aquasat are on the supply side and elbows down and to the right

Ball valve and hose cock on return and elbow down and to the left

Jason Quinn

Charlie is correct

It's not piped correctly. The circulator should be as low/close to the floor as possible to take advantage of the weight of the water adding pressure to the suction side of the pump. It also should have a bypass between the supply and return to temper the water going to the hot water zone. Make sure the strainer is not on the inlet side of the pump; this will cause a pressure drop possibly leading to cavitation which could destroy the pump. Bronze B&G 100 circulator is a better fit for this application as well.

surfsup

Thanks

Thank you for your help. I got the answer I needed not the one I was looking for though.

Mark N

Hot water loop

Put your cursor on the systems tab at the top of the page and click on Hot Water. Then click on Condensate Hot Water Heating. Read the article, look at the diagrams. Draw a diagram of your hot water loop and compare it to the diagrams in the article. Figure out whats wrong

Long Beach Ed

Similar

Your system is very similar to one we just installed. 



Perhaps steam is getting into the system or rather the heated water is flashing to steam in the pump which leads you to a void in the loop.  



All the advice above is right on the money, though it may not be all necessary to make this thing work. 



As Jason commented, you want that pump down low by the floor, or at least a foot below the boiler tapping.  On an atmospheric gas boiler, this puts the pump about a two feet below the water line.  We come right out of the boiler and drop straight down to the floor.  That would be the first change I would make, and hopefully it would clear up the problem by increasing the pressure in the loop.  



If it doesn't, I'd pipe that bypass to lower the temperature of the water getting to the pump.  



Lastly, a bronze or stainless circulator should last longer, though we've had those little iron Tacos last for years with no problems if the boiler is kept clean. 



You mat also consider the location of the acquastat on the water loop.  Seems that even if the boiler water were already hot from steaming, the pump would have to come on to supply heat to the aquastat.  If that's how it's set up, the aquastat would be better placed in the boiler, if there's room for it. 



Hope this helps.

Mannu

connecting aquastat and circulator

so when the thermostat for the loop calls for heat and the aquastat isnt at the desired temp, the boiler should go on and the water should start pumping. My question is, how do you connect the thermostat to the aquastat/circulator to the boiler itself?

Long Beach Ed

Connections

Wow, this is an old thread. 



You'd use a separate relay to control the circulator/aquastat and boiler burner from the loop's thermostat.   Most any kind used in heating applications would work.