What did I do ?

Tony_23

The return to the boiler is closest to the return of the zone. The supply from the boiler is closest to the primary loop's circ.

Could it be that the head in the monoflo is great enough to cause the flow in the close tees to reverse because of the secondary circ overcoming the primary's flow ? If so, how come the trunk flows ? How come the 008 didn't do it ?

Maybe I need to increase my P/S header diameter to allow flow in both directions ?

Tony_23

Seemingly simple

I'm puzzled.

We removed a CI Dunkirk and a wood-fired steel boiler and installed a W-M Ultra w/ IDWH.

Old system had 3 zones circulated by a 007 on the return of the Dunkirk pushing thru both boilers all the time, then to the emitters. Two zones are bbd fin, series loops. Main zone is steel radiant bbd, similar to today's aluminum but with a much higher water content and resembling CI bbd. Main zone is also an iron pipe diverter tee system, with the mains in the attic as the house is on a slab. The distance between the tees is the same as the length of bbd on each run.

I get flow thru the mains. It will start to heat the bbd's, then stop w/o any apparent reason. Mains are highest point and are not airbound. DeltaT across mains is only 2-5F at this point. If I get things cooled down, it starts to flow again. For a while...

The old system, on wood, worked best if they let the boiler heat to 180 then turned on the circ. The gas they operated normally and it worked fine.

I've changed the near-boiler piping system to P/S and now pump away from PONPC. I've tried a 008 and a 007. I've raised system PSI to 20+. Everything is bled. ODR is on a 80-190 curve w/ a 30 minute boost. Fin bbd works like a champ.

I'm missing something and am too tired to see it....

TIA for any and all help.

Tony

kevin coppinger_4

is the flow reversed?

do you have any pictures? Try to draw it out for yourself the way it was and then what you have...it sounds like an issue w/ the boiler and flow rate than the pump by itself...kpc

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Ken_40

I would double check the P/S piping...

The direction of flow to and from the W/M to the primary loop is critical for purposes of "flow" and ultimately performance of the entire system.

Pipe size and points of connection from and between the P/S piping is not always possible as the manufacturer's schematic drawings may want. The dynamics of the P/S circulators (head and GPM) are as crucial as the size and piping arrays possible as anything else.

Dbl check the flow patterns in your mind and make sure the direction of flow at the P/S inter-relational "point" is "logical" in all ways.

I have installed more than my share of these and have found I did not pay close enough attention to pump head/GPM vs. pipe diameter selections and the connections thereto to get the flow rates I thought would result.

Mia culpa. Sounds like you made the same mistale I did (;-o)

Tony_23

The wierd thing is

The "monoflo" main circulates fine and the panels start to heat up until the temp climbs and then it stops flowing thru the panels. The 007 seems to flow better than the 008, which handles a higher head. A 007 was on it before and worked. Now, the 007 in the primary only circs the zones and the header w/o BOTH old boilers and 25' of 1-1/4M. I would think that 6' of 1" and 5 90's would flow as well as that much 1-1/4 plus 8 90's and 2 tees. My close tees from the Ultra have a 2-1/4" piece of tube between them and the outlet of the boiler is closest to the supply side of the primary loop.
I thought maybe the 008 was moving water too fast ?

It seems that the cold water in the panels just doesn't want to come up against the hotter main, and just sits there. This is like a basement rad in how it's piped.

The guy before me was convinced of it air locking, and had the infamous "boiler drain bleeder" piped into 2 of the branch returns in the attic Too bad the mains are the highest points.

Tony

Ken_40

Just because the monoflo trunk...

gets hot from start to finish, does NOT mean the P/S pump/piping relationship is correct!

If you have any conflicts at the point where primary and secondary flow joins, or diverts, it could REDUCE the primary circulator's flow rate hugely! Think about the loop of the secondary - boiler circulator. When the two water-flows are merged, is the boiler pump flow in the common piping counterflowed to the main flow direction?

Bob Sweet

Not sure if this will help

but it's worth a try. Had somewhat of similar situation friday.

New const. job boiler on pri loop, 5 sec. loops, not all sec. loops are being used at this time, were looking for temp heat to lay wood floors. Fired up boiler, pri loop heated up well, as soon as I kicked on the sec. loop the closely spaced tees for the sec. loop would go ice cold and all flow in the pri loop stopped. At first I thought I had a pressure drop issue, but after purging the heck out of the sec. loop as well as the pri. loop, it appears that I had a lack of water volume in the sec. loops (due to the fact that all loops were not being used) and when the sec. pump kicked on An air lock would develop between the tees for the sec. So after some very tense moments of second guessing myself, it came down to an air lock in the secondary circuit.



To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

brucewo1b

Tony first

are there to monoflow tees on each section of radiation and do you have a way to purge each outlet leg indiviually. If you have two monoflow tees on each leg let the loop cool down raise the pressure and see if you can get the air to move out of the return risers back to the monoloop while circulatimg cool water.