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Question DetailsAsked on 2/14/2017

How many burners is ameristar 80%

Trying to buy proper furnace for house

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1 Answer


Why care about the number of burners - which is varies with the BTU rating of the furnace (typically ranging from 3 or so on up to as many as 8 for very large units) and the manufacturer's design preferences - some like few burners (sometimes with two-sided orifices), others use larger but fewer burner tubes - sometimes with slotted gas orifices rather than jets or even in at least one case a grillage system to spread the gas out over a more uniform flame - and I have seen one with probably about 40 burner jets. There are a lot of variations out there which affect the number of burners, but that is not something for the consumer to worry about - the unit rated heating capacity and efficiency are the important things - in addition to proper fan backpressure and airflow rating curves matching to your ducting demands.

To size the furnace your Heating and A/C contractor has to run through the ACCA Manual J and S calculations, and check the Manual D calcs too to check for fan sizing suitability. Manual J determines the /configuration and insulation effectiveness and such, Manual S figures the sizing of the furnace including taking into account the operating efficiency of the unit and I think whether it is operating off indoor or outside air (that may be in J - I don't remember offhand), Manual D sizes the ducts but comes into play when putting in a new furnace to check that the existing ducting is properly sized for the furnace. If undersized, sometimes the fan in the furnace has to be changed out for a higher pressure and/or airflow one - sometimes that can be accomodated with a fan unit replacement in the new unit, in others it means choosing a different furnace model.

And of course if this is a new installation (not a replacement furnace) then the full Manual D needs to be run through to size the ducting to direct the air to the right places - and to design zoning if a multi-zone system.

Without these calculations being done there is a significant chance of getting an under or oversized unit - both of which cause problems.

Heating and A/C is the Search the List category for this type of work.

Answered 3 years ago by LCD

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