Hello all, I recently picked up a vacation home and am getting everything sorted out, including the heating system. The home is pretty remote and there isn't access to professional HVAC service providers. The previous owner might have also been Micky Mouse. For example, the installed filter was literally half the proper size - amazing it didn't fly into the fan.
It's operating well now, but pressure switch two (differential switch) is not connected. Pressure switch one (not differential; single hose) is installed and monitoring the inducer fan (assumed negative pressure, but there are a couple taps on the inducer housing), and proves correctly, allowing operation. There is proper gas pressure at the input and output of the gas valve, and a nice blue flame. I bore scoped the primary and secondary heat exchangers and they are amazingly clean. There is a lot of air volume coming out of the exhaust PVC snorkel (actually pretty loud; might need a muffler at some point). I checked for CO in the conditioned space air stream and it's clean.
I found pressure switch two (differential) is not connected electrically, but is connected pneumatically across the secondary heat exchanger. There is a hose connection at the entrance and exit of the secondary heat exchanger. At first, I was thinking the differential pressure switch had it's two connections connected at the inlet and outlet of the secondary pressure switch. Connected like that, it will not prove, I suspect because there is not a large enough pressure drop. I can hear the switch when I blow into the tube (confirmed by multimeter).
Pressure switch one and two are supposed to be electrically in series based on the circuit board cover diagram, and they both need to close on pressure to activate the furnace.
After this long winded explanation, my question is this: Is there another configuration of the three pneumatic hoses that is industry standard for these furnaces?
The connections I have are:
Secondary HX inlet
Secondary HX outlet
The furnace is a York P1HDD20N11501, and I cannot find the service manual online. Does anyone have access to the service manual or can you confirm the pressure switch connections for me?
Here are some pictures of the inducer. Pressure switch one is connected to the smaller nipple that appears to be on the inside of the fan rotor, so assuming negative pressure:https://jet.com/product/detail/09f47f33380545a4896dd4b377a22c98?jcmp=pla:ggl:nj_dur_cwin_patio_garden_a1:patio_garden_outdoor_power_equipment_leaf_blowers_vacuums_a1:na:PLA_786356823_43563533160_aud-303405841869:pla-330033837354_c:na:na:na:2PLA15&code=PLA15&pid=kenshoo_int&c=786356823&is_retargeting=true&clickid=9de66940-9623-46de-9ecb-8d6d1f0f4c0e&gclid=Cj0KCQjwprbPBRCHARIsAF_7gDaN0LMFkl8M7N2bdEK_yvDEcScnrFZXe7v4r2N0-c091pgMoeJL1CMaAqNOEALw_wcB