downfire a Crown BSI103 boiler?

mitch101

A Crown rep told me my 103,000 btu Crown BSI103 (steam boiler, gas operated) cannot be downfired. I know it's oversized based on EDR (installer's mistake; he's gone to the other world since). I put two Gorton #1's at end of main (though tee-d to a small 3/8" nipple) and still short cycle. Crown should know, end of story, but has anyone downfired one or something similar anyway? The only way I can reduce (but not eliminate) short cycling is leaving thermostat at 70 degrees 24 hours a day so it only has to fire from 69 to 70 occasionally. My cutout is 1.5 and cut in .5.

EBEBRATT-Ed

If Crown says no that doesen't mean it can't be done but whoever does the work assumes the liability.

If you want to experiment, pull one burner and plug the manifold. Don't destroy anything so you can put it back if need be.

And don't do it without doing a combustion test

Danny Scully

@mitch101, did you say “down fire” or “stage fire” to the crown rep? You can certainly stage fire these boilers. It’s a 2 stage valve that starts at 100% output then drops to 60% once a specific pressure is reached on a secondary pressuretrol (or vaporstat). I’ve done this with @EzzyT a few times.

Double D

Who makes this two stage valve? Honeywell, White Rogers? What valve are you and EzzyT using. Is the valve an actuator type like the one peerless is using on the 211 for Hi-Lo Fire?

Dave0176

I use a Honeywell VR8345Q4563 it’s a 2 stage 24V gas valve for intermittent pilot.

EzzyT

I use the Honeywell vr8345q4563 which is good up to 200,000 btus and is good for spark ignition, the robertshaw 700-053 which can be used for both standing pilot spark ignition and is good up to I think 350,00 btus, robertshaw makes a 2 stage gas valve just like the 700-053 but can go up to 700,000 btus
@Double D the gas valves used on the Peerless 211 are completely different. That gas manifold set up has I believe 2 valves and 2 regulators

Double D

Thank you @Dave0176 & @EzzyT for sharing that info. Last year this time I put in a Peerless 211A -7 in a local church. The manual showed the gas trane exactly the way EzzyT describes but the one I was looking at was not the same. Assuming they sent the wrong one with the boiler, I called Peerless. They told me they now stage the burner with a Honeywell V4062 Hi-Lo-Off Fluid Power Gas Valve Actuator, we just haven't updated the manual yet. It's a line voltage control valve and I stage the valve with 2 Vaporstats. It works great.

EBEBRATT-Ed

@Double D the V4062 has been used for years (probably around 40) but is expensive and only for commercial use.

@Danny Scully , @EzzyT , @Dave0176

Just a question. When you stage fire I am assuming the manifold pressure drops due to the fixed orfices in the burner and restricted gas flow in the valve.

Does the valve have a low fire adjustment?? How low can you go with low fire before running into burner flashback problems??

Any combustion issues dropping the gas down and ccombustion air remaining the same

Dave0176

EBEBRATT-Ed said:

@Double D the V4062 has been used for years (probably around 40) but is expensive and only for commercial use.

@Danny Scully , @EzzyT , @Dave0176

Just a question. When you stage fire I am assuming the manifold pressure drops due to the fixed orfices in the burner and restricted gas flow in the valve.

Does the valve have a low fire adjustment?? How low can you go with low fire before running into burner flashback problems??

Any combustion issues dropping the gas down and ccombustion air remaining the same

Yes there is a low fire adjustment which is usually set to around 1.7” water column at least with the Honeywell valves I use. When you test the combustion of course there is a ton of excess air. Never had no flash backs or anything, it’s basically like someone turning the dial down on your cooking stove to lower the fire.

EBEBRATT-Ed

@Dave0176 , TY

dabrakeman

So would the Honeywell vr8345q4563 be insufficient capacity for a Weil-McLain EG65 209,000BTU electronic ignition boiler? That V4062 is really expensive.

If I am oversized by 23% (169.495 determined by standing radiation) and by even more given we are empty nesters with a few upstairs radiators shut off (makes us 48% oversized) would I be better off just looking into getting the unit downfired rather than installing a two stage gas valve?