Boiler Temp/Air Handler question

TomGan

I had previously posted that I was having an issue with boiler psi hitting 30 and triggering the pressure release valve. Replacing water heater fixed that problem (there was a pin hole leak in coils of my 16 year old WH that was replaced). However, while being serviced, the plumber noted my boiler had been burning hot (temp was set to 190 degrees). He reset to 180 degrees which appears to be the normal residential setting. All has been good with the psi and heating so far.

However, I have an air handler/blower in my attic which blows the hot air heat to the second level of my house. On cold nights I noticed that the blower seems to be running longer then it did in the past. I assume this is because of the boiler temp being lowered 10 degrees.

My question - is it a problem that the attic blower seems to be running long? Will that strain the motor? What is the expected life of an air handler? Any thoughts/advice appreciated.

pecmsg

Starting and stopping is hard on motors. You should have an outdoor reset to control the water temperature and better match the heat loss and give longer run times.
If your hearing the air flow there's duct issues or the fan is set too high.

TomGan

I'm not hearing air flow. In fact, the air flow seems a little light. The duct-work was put in 16 years ago. Does duct-work need to be inspected and repaired over time?

pecmsg

TomGan said:

I'm not hearing air flow. In fact, the air flow seems a little light. The duct-work was put in 16 years ago. Does duct-work need to be inspected and repaired over time?

Flex duct if not installed properly yes it might need some straightening. Ridged metal unless damaged holds up a long time.

190° water is high and rarely needed. Here's a post on outdoor reset: https://forum.heatinghelp.com/discussion/72300/is-boiler-outdoor-reset-control-worthwhile-for-residential

STEVEusaPA

In the OP's case, I wouldn't bother with ODR-Weil McClain Oil, air handler, probably improperly piped for boiler protection.
The shoulder seasons the target will be 140° (min), will creep up to and eventual 160°. Maybe hit 180° no more than 5 days. And that's only if the heat can get distributed efficiently. The air handler won't like the lower temperatures, and will create even a higher delta T on that zone, fighting against the boiler minimum.

Oil (probably oversized-especially if zoned)/zoned/no buffer tank-no benefit with ODR-has been my experience.

pecmsg

Just the energy savings and longer run times make it worth perusing. There could be other issues as well. Need to be there to see.

GW

I’m with Steve- longer run time for an attic system doesn’t seem good. No attic system is good to begin with. The fans prolly pull a two or three amps as well, maybe 4 or 5 if it’s a hog. Cold attic air is killing off efficiency in a attic system. My thinking is hit it, make the stat happy, kill it. Maybe 30 seconds of post run, or no post run.

Inspect ducts——normally not, only if something isn’t happening. But post purge fan time is a different topic

Anyway - your fan- tough to say. It depends on what exactly is telling the motor to stop. If it’s a timed event then there should be nothing different. It’s it a mechanic pipe sensor (aquastat), then that should be adjustable, perhaps

You may need an hvac person if the plumber guy can’t answer your questions

TomGan

GW - Thanks, I think I will have an HVAC guy come in. I just checked out your web-site. Unfortunately, I'm outside your service area. Can you recommend anyone good that services Northwest Connecticut? I'm on the CT/MA state line. Do you think keeping boiler temp setting at 190 is too high? Should I set to 180?

STEVEusaPA

pecmsg said:

Just the energy savings and longer run times make it worth perusing. There could be other issues as well. Need to be there to see.

I agree, but with this set up, you'll get short cycling as the boiler will heat the water too fast, faster than it can be used, and the OP will constantly bounce off the high limit, or the reset limit.
A mild or not so mild day, boiler reset to its minimum of 140° or even 160°, one zone calling, very oversized boiler--short cycling.
Unless you use a buffer tank.

pecmsg

We don't know what the OP has? Properly or oversized. (My $'s on oversized 75% or greater) That's why I stated the OP needs someone there that knows.

JUGHNE

OP's main concern was the longer run time of attic blower.
IMO, less starts with longer run time is better on the motor.
Many systems have blowers running 24/7 or nearly so.

TomGan

Thank you Jughne. Yes, that was my primary concern. Appreciate the response.

hot_rod

If everything was designed, sized and installed properly a heat emitter would run 24/7 on design days, that is not a bad thing.

Also the lower the SWT the more efficient your boiler is.

If it keeps up with the heat load, let it rip.

Some day you could replace the fan motor with an EMC and cut power consumption. You would want to assure the ducting is correct so the motor works in its happy range.

Variable speed blowers are really nice, they modulate, and quiet down while providing constant heat flow matching the load near exactly. Air filtration, humidity control, etc.

GW

180 is the accepted standard. 190 is fine but it seems to be a bit hot, and you’re wasting some fuel (the hotter the stuff the more that goes up the chimney on the “off cycles”)

GW

If you did not have an attic air handler system, I might be mentioning and suggesting different ideas.

bburd

Good grief, gentlemen… 180° is the design supply water temp for most hydro air systems. The attic heating coil was almost certainly sized accordingly.

Yes, the fan motor will run a bit longer, and use a tad more electricity, than with the supply temp at 190°—which slightly reduces boiler efficiency (higher stack temp and standby losses) and will use a tad more fuel. It’s a tradeoff.

The OP’s system isn’t broken, and he doesn’t need to fix it!