The Crystal Fire® Burner Design does not require High Altitude Adjustments. Complete explanation below: In the standards today there are requirements for de rating the input of a gas appliance in high altitude applications. The reason for this is gas appliance performance is affected by the available amount of oxygen in each cubic foot of air as you increase elevation. The requirement in the US for a 4% de rate for every increase of 1000’ of elevation has been around some time. But there are a number of things that make the calculations and need for this more complicated than just changing the orifice to reduce flow by 4%/1000’. Things like the gas being de rated by the gas company (by adding nitrogen to the mix to reduce the actual BTU content), pressures altering the amount of flow through an orifice, the type of appliance being power vented or open atmosphere. The actual tested input rate performed by the lab. In Canada you are allowed to increase your input for combustion to simulate high altitude installations. Regulations have some appliances exempted from the reduction in rate such as outdoor BBQ grills. Some manufactures de-rate their appliances at the factory to allow for a not having to de rate in the field.
The technical reason for the de rate is the reduced amount of oxygen can cause more CO creation during combustion than during normal elevation operation. This is caused by restricted amounts of air being supplied to the combustion area for primary and secondary air. Other issues causing a higher CO production can be the design of the burner, combustion chamber and the heat exchanger. The manufacturer is designing to meet government requirement for efficiency, safety standard requirements along with the need to be price competitive. So a product can become complex trying to accommodate every situation without requiring some modifications for the environment it is installed in.
When it comes to outdoor- free air- no combustion chamber- appliances, the need for de rate becomes less important. There is plenty of air for combustion, the combustion chamber is limitless so no impingement from slower burning taller flames, no heat exchanger or vent to restrict air from entering or exhaust from escaping. And all the outdoors for dilution of combustion products to prevent the possibility of high CO or exhaust concentrations anywhere. If you compare to a wood burning fire pit that may be burning closer to 2 million BTUs/hr. and a natural gas or LP gas burning appliance at 100,000btu/hr. There is virtually no exhaust to contend with or CO of any comparison to wood.
It is of course important to start with a listed product, these are tested to ensure proper lighting, combustion, and construction. Where a non-listed burner will not provide a known starting point for these safety areas.
At OGC we start with a listed burner and increase input well beyond the rated input of the burner to ensure that our burners are not going to require a de rate in the field for altitude. But we are not the final authority when it comes to installation in the field. You must follow all the requirements of your local jurisdiction when installing any gas appliance in the field. If the local authority requires de rate we can help you meet those requirements.