Find Out Where the Ignition Sequence Stops
Go through inducer, pressure switch, igniter, gas valve and flame sensor in order and see exactly where it quits.
System Diagnostics
Get No-Heat Boiler Calls Sorted Without Guessing
From old cast iron to condensing mod-cons, ACLogics tells you whether to look at the electrical side or the water side first.
FAULT SYMPTOM
Low suction pressure
CHECK 01
Measure Evaporator Temperature Drop (Delta-T). What is the temperature drop across the coil?
High Drop (Above 22°F)
DIAGNOSIS
Dirty air filter, closed supply registers, or low speed blower.
Low Drop (Below 16°F)
CHECK 02
Measure Superheat and Subcooling. What are your readings?
High Superheat, Low SubcoolingLow Superheat, High Subcooling
Complete diagnostic tree — every branch, every fault path
Try ACLogics Free — iPhone & AndroidWhat You'll Stop Guessing About
Know what failed before you order the part.
Get Air Out of the Loop and the Heat Back On
Sort out air-bound loops, circulator failures and expansion tank problems without trial and error.
Know Which Safety Shut It Down
Narrow it to the low water cutoff, aquastat or high limit before you start replacing controls.
How a Call Goes
01
Pick the Boiler Type
Standard, mid-efficiency or condensing: the checks follow the boiler in front of you.
02
Rule Out Electrical or Water-Side
Get clear, ordered tests that separate an electrical fault from a flow problem.
03
Confirm It's Heating Right
Check water temperature, pressure and combustion before you leave.
Frequently Asked Questions
Why is one radiator always cold?
This is usually air trapped in the loop or a seized zone valve. We guide you through purging procedures and electrical verification of actuator heads.
The boiler fires but rapid cycles. What causes this?
Short cycling can be caused by dirt in the filter (if applicable), improper anticipator setting, or oversized equipment. We help check flow rates and delta-T.
Does this cover steam boilers?
Yes, we include specific checks for sight glass levels, pressuretrol settings, and pigtail siphon blockages common in steam systems.
Know What to Check Next on Your Next Call
Get the checks in order, confirm the cause, and fix it right the first time.