Gas furnace problem

[senior_op]

When the thermostat for my gas furnace is turned up after being down overnight, the auto ignition pilot light ignites ok. But, only three of the four main burners light at first, ...the fourth one, which is furthest from control valve, lights 2-3 seconds later with a "whoosh" of flame (very disconcerting!) It doesn't happen all the time, only if furnace hasn't run for a while. I've pulled the cover plate from in front of the burners and vacuumed the tops of the burners (even tho there was no visible debris) but it didn't help. Any ideas?.... Someone mentioned that the gas pressure may be too low. If this is true, how do I turn it up? The control valve is a Robertshaw-Grayson 7100 der - 27C.

[HayZee518]

If you are on city gas I'm afraid you have no option but to go with whatever pressure they are supplying. If you have LP then the regulator coming off your tank is also preset for a certain pressure in inches of mercury [gauge] a licensed gas person maybe able to adjust this pressure - a DIY isn't recommended to do this. LP and Natural gas mixes with air to form a combustable mixture at the burner. It just takes a while for the mix to reach the burner head.