HydroPulse A50 "short cycling"

lodefinition

NB: I'm a brand new "wall" member. I don't see the post I just attempted.

This is my 2nd attempt to post. (I apologize if 2 identical posts show up).

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Subject says it all... HydroPulse A50 "short cycling".

Installed, 10/15/1981; NatGas, Constant Circulation.

Been running fine, but recently has been short cycling.

In AM from t'stat nighttime set-back, will run fine for ~1 hr

but as return water temp climbs to ~100F, suddenly shuts down,

but as t'stat still calling for heat, *immediately* initiates start-up cycle.

• Table fans blow on radiators (lowers return water temp) seems to help.

• Air valve discs & spark plug changed ~2 yrs ago (prior to that all original).

• Dual high limit temp switch appears Ok (does not trip).

• Water jacket not leaking (w supply shut-off, pressure holds).

• Exhaust piping appears clear (no PVC changes in 30 yrs).

• Condensate drain: 0.132" toilet stopper lifting rod, after getting hung-up just a bit, goes in 5". (NB: Threaded end of rod cleaned something, maybe a bit of scale(?).)

• I'm aware of fire-side flash-tube muriatic acid flushing maint for propane-fired units, but I'm not aware of a need to do this on a NatGas fired unit. (Yes? No?)

• Boiler now has on the order of 26k hrs on its clock (Yes, I installed meter in 1981)

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If it'll help, I have an audio file of the exhaust sound; I do not think it's "motor boating"; honestly, not sure what that sound might actually be, but unit sounds 'normal' to me.

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Suggestions? Thx, lodefinition [Jeremy]

Slimpickins

Bad blower

My guess is the blower is bad if its original. Personally I'd recommend replacing the boiler, you've gotten your money's worth out of it. You can get better efficiency with a new mod/con boiler with reset and plus way less noisy. Your wife and neighbor will love that!

lodefinition

Thx Slimpickins

Ok, problem resolved (more info below).

Note: *Can't* be blower, HydroPulse blower *doesn't* run after boiler has been firing.

Further, not to get into a long discussion, but since HydroPulse doesn't use electricity while running (only uses 112ma to hold gas valve on, so ~12W), current generation of condensing boilers are not as efficient as HydroPulse, since they (in contrast) all use blowers while in operation... ie, overall they use more *total* energy.

As for the noise, mine is installed under under kitchen, but when our refrigerator is running, you literally cant tell IF the HydroPulse is on, or not... ie, it is *not* noisy. (I suspect noise issue complaints are due to various installation issues.)

Lastly, I run constant circulation... so using outdoor reset would be redundant... my circulated water temp already is as low as it can possibly be. (I don't know why more people don/t use constant circulation; simple, return water temp lowest so maximum condensing mode. My return water is typ ~80-90F... really. (I have a separate gauge.) Note:

lodefinition

Reply continused...

(New user... Ack! When posts are long, are they truncated?)

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lodefinition

One more time...

(New user... Ack! When posts are long, are they truncated?)

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lodefinition

Still trying to append truncated post...

(New user... Ack! When posts are long, are they truncated?)

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lodefinition

Sigh... I give up!

Short answer, it was high temp limit sw bouncing.