20 Most Recent Hayward H-series Electronic Gas Pool Heater H300 Questions & Answers

may be a faulty pressure switch. the code LO represents not enough water flow for the unit to run. check for blocked lines. remove the supply\return lines to heater and make sure the shipping caps were removed (seen that happen) page 38 of your owners manual

Could be either the pressure switch(tells the heater that there is suitable amount of water flowing the startup the ignition), hi limit switches, or low vent pressure(if you have a exhaust fan installed for the model. Easiest thing to try is to give the pool filter a good backwash. If this doesnt solve the problem, than the above electrical components need to be looked at and singled out

Try cleaning the filter.

Hayward H series with ED option have electronic ignition with one or two dial thermostats. Along with thermostats, there are other temperature safety switches to shutdown the heater in case of over temperature, both for water temperature and for interior cabinet temperature. CAUTION: Always turn off power, gas and the water pump whenever repairing your Hayward H series pool heater. CAUTION: The Hayward H series pool heater is essentially a gas furnace. Only a qualified technician with proper training and tools should make repairs of your heater. I'm assuming you are seeking the location for the thermostat sensor rather than the temperature switches, and I'm assuming you have dial-style thermostat(s). Incoming water temperature is measured at the inlet of the water heat exchanger. For most H series models, provision is made for two thermowells. If your unit has dual thermostats, both of these wells will have a bulb-style sensor inserted directly into the thermowells. If only one thermostat, then one of the thermowell ports will be sealed with a plug. The factory orientation of the water inlet and outlet is on the right side of the heater (as you face the front), but the installer has the option to locate the inlet/outlet on the left side with a field modification. Check your particular inlet/outlet orientation for either right or left side. The heat exchanger thermowells and the thermostat sensors are located directly behind a two metal access plates that surrounds the heat exchanger inlet and outlet ports. Several Phillips-style screws secure the access plates to the heater cabinet. After several years of outside operation, these screws will likely be corroded and need some anti-rust oil to aid in their removal. When you have completed your examination of the thermowells and thermostat bulbs, I recommend applying some grease to the screws before re-assembly. Once the access plates have been removed, the thermo-wells can be seen on the left side of the heat exchanger, which is the inlet side. Use the arrows on the top of the heat exchanger as a guide for inlet an outlet. The thermostat sensor bulb is directly inserted into the thermowell without any securing mechanism other than a copper or brass friction strip. I have seen some situations where a small amount of fiberglass has been inserted behind the bulb. The bulb should be inserted all the way into the thermowell until it touches the back. The copper or brass strip is used to keep the bulb in contact with the sides of the thermowell. (For non-dial thermostat systems, the inlet water temperature measurement is made in the same location, but with a different device.) CAUTION: The thermostat sensor is a liquid-filled thermo-expansion sensor. It relies on the thermo-expansion properties of a non-compressible fluid to operate the thermostat switch. Take care to not crush or kink the capillary tube between the sensor bulb and the dial thermostat switch. If you remove the sensor bulb, take care to capture the copper/brass strip in order to use during re-insertion. NOTE: Thermowells are sized to the particular thermostat sensor bulb. If you replace the thermostat sensor be sure to use the same size sensor bulb as the one being removed. If this is not possible, the thermowell may also need to be replaced. Check your manual for verification of part numbers. The H series dial thermostat part number is CHXTSW1931. The matching thermowell is CHXTBW1930.

check gas pressure if not adequate that heater will not run you might need a bigger gas meter call gas company add all your appliances that use gas there should be plates on all gas appliances add those up and give that number to the gas company

That is the drain plug...underside of the inlet/outlet header. You should also break open the connection of the water tube to the pressure switch inside the heater to prevent the switch or tube from freeze damage.

John

replace pilot generator

With a symptom like this I recommendyou call the Hayward technical support at 908-355-7995and they might be able to help you figure this issue out. Ihope this helps.