Okay. My neighbor is having some kind of problem with his new boiler. Same plumbing as before- just attached at the boiler. At the furnace plenum, intake and outgo pipes are good and hot, but when the furnace fan is on, there is a significant temperature drop on the return line. Of course it doesn’t warm the house either. thoughts? He is pretty handy, and installed his complete boiler before. Frustrated with it
Random guess; circulation pump for the water is too slow. Not moving enough water before the furnace fan strips the heat in the heat exchanger? I would think the furnace fan and heat exchanger should already be match together.
Jeffrey Svoboda yes the fan exchange been matched for ten years. I think he is using the same Taco pump from the previous boiler.
Sounds like low flow on the line set from the boiler to the water to air heat exchanger. Could be the pump or the heat exchanger.
Confused here. My understanding is a furnace is used for forced hot air, which we have. A boiler is for baseboard heating. I've not heard of a boiler with a fan. I'm probably displaying my ignorance in such matters.
Seems like primary heat source is forced hot air. Boiler is rigged up to provide hot water to heat exchanger at furnace plenum so HVAC can distribute hot air. I would also think low flow to heat exchanger. What kind of boiler is the new boiler? What was in there before? What is the temp as the water enters and exits the heat exchanger?
The issue sounds like low flow to me. The return water is so cool because there is too little water flowing through the exchanger, therefore the temperature delta of the exchanger is very high. A plugged exchanger is possible, but does not make sense if his old boiler did not have the same problem. Air lock sounds like a likely problem. Is it plumbed in a way that he can do a power flush?
MikeInMa No, outdoor boilers operate on forced air heaters. No need to go into further details at the moment.. plcnut No idea on a powerflush. He replaced his Classic with an EZ All system was operating fine before, Just attached existing plumbing to the new boiler Now my boiler pump is out for the third time since December. Tech is coming again. He is wondering if there is a restriction somewhere. It heats fine and then it’s out
What brand of pump are you running? Is in mounted correctly? What is going bad when it dies? Windings? seals/bearings?
He probably has an air lock in his heat exchanger. I put a T in my basement so I can push all of the air in the lines out to the boiler via domestic water pressure. Hopefully his circulator is on his boiler and not in the basement. If it is, that's a whole other can of worms.
T is a Taco. The first one went out after 8 years . The replacement was running slow and making a louder noise than normal. They replaced the cartridge u der warranty. This time it was making no noise. The tech replaced it with a different model Taco . there were no problems with heat performance so no restrictions are overworking the pump
I have been happy with Taco pumps. Your last failure sounds like a winding problem. Most other failures lead to excess noise. Hopefully you are just dealing with faulty parts and your new pump will last. I do know that if the shaft is not horizontal you are likely to have issues. Also, if the flow through your pump is down, then you need to take extra precautions to ensure no air gets to the pump. When pumping downhill then air bubbles can sit in the pump and slow the flow which can lead to overheating of the pump. I prefer for flow to be up whenever possible so that any air in the system will flow past the impeller.
Depending on pump speed, I see about 15 - 20F across the HX in my furnace. I'd expect the OP to see something similar.
I'd have to look up the pump rating...the boiler is rated at 600k BTU, but we have the burner turned down.
We are dealing with 1" lines all throughout the system I hope? Sometimes, a DIY will buy a less expensive heat exchanger with smaller than 1" connectors. Also, I think you mentioned that the heat exchanger is sized (btu output) for the house also? Can't remember
Only thing that has changed from before (when it worked) is the boiler itself...I still say there's air in it
