primary/secondary problem

Tremmelle

just installed a primary/secondary system using a Trinity T150 boiler. There is a B&G NRFcirc on the boiler loop (3/4 copper), A B&G 101 series ( I think that's right..It's huge compared to the NRFs...It's left over from the previous system.) on the pri loop. The pri loop is 1 and 1/4 copper and is 50 feet in total length. There are two zone loops both with NRF circs and 1 inch copper.

The problem is that the returns for the zones are not getting hot. Can this be because the circ on the prim loop is too big? The T's for the boiler loop are spaced 5 inches apart, and zone loop T's are within 5 inches of each other and there are check valves on feed and returns on all loops .

Any ideas? I guess I should say that I'm a doityerselfer, so please be gentle.

Unknown

The returns aren't getting hot?

Is the radiation getting hot? You might be airbound. If the radiation is hot, how long is the radiation loop; and what size radiation is it?

On another note, how much heat are you trying to get out of the 3/4" boiler piping? What are the boiler supply and return temperatures of the boiler loop?

Noel

Tremmelle

The baseboard radiators are not getting hot at all. So in other words, the supply pipes appears to be getting hot because of proximity to the primary loop, not because of flow. The radiators were all bled without any issues. The zone loops are approximately 100 feet each with 1" pipe. There are two zone loops. Is it possible that the circ on the Primary loop is too powerful and is blowing right past the T's. Although I would think the zone circ would make that a mute point. I can't imagine what else it can be.

The Boiler is rated up to 150,000 BTU's, but has 3/4 in and outs.

Tremmelle

forgot to mention that the temps as read on the digital display that is on the boiler is showing 170 degrees as the boiler water temp

Unknown

I think

From what you describe, the flow problem is in the secondary loops, the heat zones. If a zone's supply tee and it's return tee are right together, with nothing in between, the pump in the primary loop exerts the same pressure on both tees (almost) and has no effect on flow in the heat zone. The zone circulator pump and the check valves and the air and water in the zone are the only things that cause flow or no flow in the zone.

Do you have 170° F. water flowing in the primary loop?

Is your return water to the boiler 170°?

Since the boiler is a seperate loop than the primary loop, and the piping in and out of the boiler is VERY small, I can't infer from the boiler temperature what the primary loop temperature is, or what the baseboard loops temperatures are.

It is possible that you do have circulation of water that isn't hot, or that you don't have circulation at all.

Noel

Tremmelle

the 170 is from the internal gauge for the boiler temp. You are correct in assuming this is not the temp in the primary loop. I spoke with the Trinity distributor a while ago, and was able to give him a lot more details than I've written here and he agreed with your earlier assessment that it's air. He described a much more detailed method for the expulsion of air than the way I did it, which was just bleeding the valves on the radiators. Stay tuned and thanks!

eleft(retired)

primary/secondary problem

Tremmelle,



Is there a slotted screw head in the side of the pump flanges?


al

Scott06

Have you checked the way the circulator and flow checks were installed. Have you checked to make sure that they were installed with the flow and not against it. Could be as simple as that or maybe airbound.