Coil will not heat properly (all coil types)

1) Supply problems, no steam/hot water.
CAUSE	SOLUTION
Steam/hot water source is blocked by shut off valves.	Verify that all valves preceding coil are open and supply is available to coil.
Plugged strainer.	Open and clean strainer.
Defective trap or mis-sized trap.	Repair or replace trap.
Solenoid valve not connected to terminal blocks in control.	Connect as required.
Solenoid coil voltage does not match power supply.	Replace solenoid valve or coil to match available power.
Improper wiring/voltage not jumpered to isolated contacts of control.	Verify wiring with appropriate diagram and correct if necessary.
Incorrect thermostat settings.	Verify thermostat settings and switch operation, repair or replace as required.
Defective temperature control/sensor.	Verify temperature control operation, repair or replace as required.
2) Valve not turning on.
CAUSE	SOLUTION
Solenoid valve electric operator coil open/burned out.	Test operator coil by applying rated voltage and replace coil or valve as required.
Solenoid valve stuck in closed position by deposits.	Clean/repair valve if possible. Install strainer on inlet supply prior to valve to reduce particulate matter flowing through valve.
Low pressure. (Many pilot operated solenoid valves require 5 PSIG minimum pressure drop across valve to operate.)	Increase pressure on supply or replace valve with a zero pressure drop model valve.
N/O solenoid valve used instead of N/C valve.	Verify valve operation and replace as required.
3) Reduced output of coil. Any time reduced output of a coil is suspected, tests should be performed to measure the pressure and temperature of the incoming source and amount of condensate or temperature of output water.
CAUSE	SOLUTION
Low steam pressure. (Any pressure below the design rating of the coil significantly reduces the rated output of the exchanger.)	Measure the available pressure and compare it to the rating on the tag. Check and compare your incoming pressure at the boiler vs. the pressure at the coil. If the difference exceeds 3 psi consider increasing the pipe size or adding insulation. Either add additional coils or replace the coil with a larger one to add more exchanger surface area to increase capacity.
Temperature control sensor not located properly in tank.	Place/secure sensor 1/3 of way down in solution (preferably within a thermal well).
Steam pressure too low for proper operation of standard pilot operated valve..	Increase steam pressure at the valve or install a direct acting or zero pressure differential valve in its place.
Coils plumbed in series. (This condition would cause each successive coil to produce less than the rated output while increasing the pressure drop and condensate on the system substantially.)	Reconnect coils in parallel to an appropriately sized header.
Water hammer damage to internal baffles within grid style coils which allows flow to bypass portions of the exchanger.	Contact factory for repair install drip trap before steam valve and water hammer arresters in supply line.
Buildup on coil sheath.	Inspect and clean coils on a regular basis appropriate to the rate of buildup from the chemistry employed. Check application, as larger/more surface area may be required in most solutions that buildup quickly.
Improperly sized exchanger.	Verify heat requirements and replace exchanger as required.
Coil not fully submersed in fluid being heated.	Fill tank to submerse coil or correct mounting or plumbing to accommodate low fluid level.
Inlet/outlet connections reversed on steam coil.	Verify inlet/outlet per installation instructions and correct connections as required.
Low temperature feed water supply (for heating). Too high temperature feed water supply for cooling.	Verify temperature of feed water and correct as required.
Steam trap installed on inlet side of coil.	Reconnect stream trap on outlet side of coil.
Plugged vent hole on steam trap.	Clean any deposits from trap vent.
Blocked strainer.	Clean or replace strainer.
Undersized supply piping.	Calculate BTU requirements for tank and corresponding rating for pipe at your system steam or water temperature and replace as required.
Undersized inlet/outlet supply tubes to coil.	Calculate BTU requirements for tanks and respective flow requirements. Rework or replace coil inlet/outlet tubes to accommodate flow.
Steam coil operated on water service. Grid style water coils require baffles to direct internal flow. (Note: Coils designed for water service will operate fine in both steam or water applications.)	Replace coil with one designed for water service.
Insulation on trap. Too much insulation on steam trap can reduce cooling rates on thermostatic traps and impede their operation.	Reduce or remove pipe insulation if trap is mounted in a protected area or replace trap with a style that does not rely on external cooling to operate.
Back pressure from condensate return on low-pressure steam systems can prevent outflow of condensate from trap.	Verify that pressure on condensate leg is below pressure on outlet of each individual coil.
Condensate return line and/or trap above exchanger.	Do not route condensate return above outlet of exchanger without condensate pump. Trap should be mounted 18" below coil outlet. Correct trap location and condensate piping as required.
Steam lock on piping between coil and trap.	Re-plumb trap 18" below exchanger outlet line with as short of horizontal pipe as possible. If problem persists, install steam lock release or trap with integral steam lock release.
Improperly sized trap.	Calculate BTU requirement for tank and verify proper trap sizing. Replace as required.
Multiple coils on single steam trap.	Each coil must have its own trap for proper operation. Verify operating parameters for each coil and install an appropriately sized trap.
Improperly sized solenoid valve.	Evaluate BTU requirement for tank and verify valve Cv rating. Replace valve as required.
Improper trap style selection.	Inverted bucket traps work fine on metal coils, however, balanced pressure or thermostatic traps perform better on fluoropolymer exchangers by reducing air binding. Replace traps as required on fluoropolymer coils.
Condensate line plumbed above exchanger causing back pressure on trap.	Re-plumb condensate return system or add condensate sump/pump to evacuate condensate.
Air-bound steam trap. Air in system both insulates and dilutes the steam reducing its temperature and forms a film on the exchanger walls limiting heat transfer.	Change trap style to one that can vent air from system faster or install a bypass bleed valve to evacuate air in line.
Unbalanced load/mixed types of coils.	Multiple coils should be plumbed to a single appropriately sized header and with valves provided to distribute/adjust each output. Combining water coils of different sizes, or non-uniform groupings will cause unbalanced pressure drops on one or more of the coils and inefficiencies.
Buildup inside exchanger sheath. Caused by particulates or colloidal materials that have accumulated on the coil interior surfaces from the water/steam source.	Dissolve away all deposits with exchanger with a chemically compatible cleaner. Install a water conditioner and strainer on the water/steam supply.
Viscous or concentrated solution. Dense or concentrated solutions impede heat flow from the sheath and can reduce performance.	Increased mixing of the solution near the coil can reduce the problem. Consider installing multiple coils and space them evenly around the tank to enhance heat distribution.
Kinked or damaged tubes.	Visually inspect all exchanger tube surfaces for dents, kinks or collapsed tubes. Repair or replace as required. Protect coil from damage with guards or move to protected location.
4) Tank contents overheating.
CAUSE	SOLUTION
Temperature control sensor below or too far from heat source.	Verify control/sensor operation and secure sensor above bottom of exchanger and near work or reinstall coil deeper in tank.
Valve stuck in open position.	Test valve operation and repair/replace as required.
Improperly sized trap causing excessive condensate and time lags in system	Verify proper trap size and type required for application and replace as required.
Defective or damaged temperature control sensor on thermostat.	Consult temperature control trouble-shooting information and repair or replace as required.
Temperature control probe mounted in air.	Verify control/sensor operation and secure sensor adjacent to coil.
Temperature control out of calibration.	Verify temperature control accuracy by placing known accurate thermometer in same location a control sensor and calibrate as required.
Heat exchanger too large for application.	Verify all heating requirements and replace exchanger as required.