Joined on February 3, 2007
Last Post on March 10, 2014
@ December 20, 2012 10:42 AM in auto feed system - necessary?Many cities require redundant low water cutoffs on commercial boilers one of them being a lwco feed valve combination. ex. ( mcdonnell miller # 51 ). Yes a boiler could dry fire if any lwco is neglected. Mc Miller recommends blowing down the lwco weekly. I found when doing boiler P/M 's that if customer could do it themselves every 2 wks that was good. I would clean or replace the strainer basket every 3 months and completely clean entire unit yearly especially the bowl float assy.
@ December 19, 2012 8:35 PM in Merry ChristmasMerry Christmas to all remember John 3:16
@ December 19, 2012 8:28 PM in What watt!My understanding is that (power factor correction ) is not used in resistive loads, In a 3 phase suppl. heater circut we add the following amps = KW x 1000 divided by volts x 1.73. On page 17 of the Ugly's book I believe they are talking about inductive, reactive loads. (motors , transformers ) I always like to get several sets of eyes on all questions.
@ December 19, 2012 11:23 AM in Tips to repair Car Air ConditionersDont forget to change the cabin filter It is fairly simple to get to on newer cars. there are some good videos on you tube
@ December 18, 2012 3:12 PM in Dual Duct VAV boxes - Inlet PressureContact your local Trane rep. ask for literature and request a I.O.M. (manual) also on yahoo look up HVAC units-Varitrane dual duct boxes. you will need some training on this one. may need Rover/comm 4 software and Rover tool
@ December 17, 2012 2:26 PM in furnace firing issueYou need a minimum of 5 inches water column to inlet of most gas valves and 3.5 inches to burner on most furnaces, these setting can change if you have a 2 stage valve and on commercial burners. most diaphram style gas valves depend on this 5inch to 3.5 inch pressure drop to operate correctly.
@ December 17, 2012 1:05 PM in furnace firing issueHave a licensed Hvac contractor check it. could be low gas press. you could start with your gas co. alot of them dont charge to check your furnace.
@ December 15, 2012 6:23 PM in Honeywell random fault lockoutYou need to maintain at least 6 inches w.c between the reg on the boiler and your parrallel regs. while the burner is operating. ( where the pilot piping is attached to the gas line ) 7 inches would be better, if you cant burner wont oper. properly. have the Gas co. meet you at the job site
@ December 15, 2012 5:29 PM in suppemental heat400 cfm for cooling and 500 cfm for heat pumps is data used in Carrier ht pump and air balance manuals, as well as many other unit manufacts. the other data came from SMACMA. I agree a 10 degree temp rise is'nt much but some of the jobs I looked at in northern CA had no suppl. heat and barely had an electrical service to the bldg big enough to support 40 amps to each unit, so a 10 degree rise was better than nothing. I do know about all the stages needed in colder climates as i started my career in Denver in 1974 and also worked in SF for 20 yrs.
@ December 15, 2012 4:54 PM in Dual Duct VAV boxes - Inlet PressureAre they DDC boxes or pneumatic. minumum static is critical, If you want vairiable air volume your boxes will need velocity controls, do they have a hot duct and cold duct run to them, need a little more info.
@ December 13, 2012 5:35 PM in Circulation pump vibration noise?Get a tech to check for pump cavitation (air in system getting into pump ) beftore replacing pump. this is what is called a maint. free pump, no coupler. If the pump is within a year old it should still be in warranty.
@ December 13, 2012 3:27 PM in Circulation pump vibration noise?could be a loose or broken coupler if its a B&G series 100 pump or taco equivalent , or a bad motor or pump bearing, it most probably will get worse. Better have a pro look at it. have the pump brand, mod, serial # and motor horse power on hand when you call.
@ December 12, 2012 6:32 PM in One Pipe Steam System FloodingNot sure if you have checked the fill valve assy. closely. Most Mcdonnel Miller LWCOs have a replaceable valve that can get corroded and plugged up allowing inlet water to seep by the valve seat, they can plug up within 3 months if you dont change or clean the strainer basket. I had a job where after 2 weeks the boiler would be flooded, found the sa-51-101-102 was corroded inside, I replaced the valve assy. on the no.51 LWCO. no more flooding. be careful with these valves as excessive water press. on valve inlet on start up can damage valve. also you should inspect the float assy. sometimes they can develope a hole or colapse. I recommend completely going through LWCO (low water cut off ) annually.
@ December 12, 2012 11:53 AM in suppemental heatI used 7.5 kw instead of 7.9 kw formula stays the same my mistake
@ December 12, 2012 11:48 AM in suppemental heatthe 10 degrees is the supply air temp. rise I would like to see during ht pump defrost mode considering the supply air temp. could be 50 deg. actually 15 -20 degees would be better. using formula for single phase, 3 phase will differ. Amps = watts divided by volts 7.5 kw (7,500 watts ) divided by 208 volts = 36 amps, or a 40 amp service. Let me Know what you think I dont want to give out wrong info
@ December 11, 2012 5:50 PM in Commercial BoilersI agree, above 399mbh considered commercial. For a number of years now in San Francisco any commercial boiler 400 mbh or higher can't be replaced with an atmospheric burner style boiler. It must have a power burner. This is to help with controlling flue gas emissions
@ December 11, 2012 5:09 PM in suppemental heatHere are some formulas that are helpful in figuring out suppl. heat on air to air heat pumps.
KW required when CFM and desired temp. rise are known ( rule of thumb 1 ton = 400-500 cfm ) KW = CFM times T.R.(temp rise) divided by 3150.
Temp. rise = KW times 3150 divided by CFM
Amps = KW times 1000 divided by volts
example A 5 ton heat pump would need a 7.9 KW heater for a 10 degree T.R. This would require a 40 amp service at 208 volts just for the supplemental heater.
@ December 11, 2012 3:58 PM in New Boiler - Hammering and Leaky Air VentsI agree with all also looks like header pipe size is reduced
@ December 11, 2012 11:09 AM in Adding a patio room zoneTaco/HVAC on the internet has great resources , they use to have pex tubing flow/press. drop charts. Taco makes a good pump you could use on your project.
@ December 10, 2012 11:48 AM in One-Pipe Steam-TRV or Better boiler controls?A Danfoss RA-2000 1 pipe valve and a G-8023 operator together run about $100.00. I have used these in old multi story office bldgs. in San Fran. with some success. The problem with this type of control is that the boiler must cycle alot and reach below 0 psig. on off cycle Dan Foss has a 1983 memo explaining this.