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Joined on February 3, 2007

Last Post on April 12, 2014

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fill valve

@ December 12, 2012 6:32 PM in One Pipe Steam System Flooding

Not 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 heat

I used 7.5 kw instead of 7.9 kw    formula stays the same    my mistake


@ December 12, 2012 11:48 AM in suppemental heat

the 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
Thanks  Rick


@ December 11, 2012 5:50 PM in Commercial Boilers

 I 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

suppemental heat

@ December 11, 2012 5:09 PM in suppemental heat

 Here 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 Vents

I agree with all    also looks like header pipe size is reduced


@ December 11, 2012 11:09 AM in Adding a patio room zone

Taco/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.


@ December 9, 2012 10:40 AM in primary secondary schematic

on yahoo  look up Taco/HVAC


@ December 8, 2012 3:00 PM in Badly plugged sections

I agree I would get someone familiar with your boiler to determine how to clean it   I would also get someone with a strong background in boilers who  can do a complete flue inspection ( proper flue size, fresh air,combustion air ) and a combustion analysis of the burner.     I would also put a co monitor in the boiler room.  Be carefull using any chemicals in boiler rm.  especially if there is other gas or  oil fired room.


@ December 8, 2012 11:32 AM in T-stats in Apts...

White Rogers makes a commercial t-stat that allows you to install 3 remote  sensors, you can set priority on different sensors   sensors are sold seperate, this is a 24volt heating cooling t-stat, in your case dont wire up cooling. I used in a 3 story bldg, I was controlling 1 reznor M.A unit, I had the t-stat on top floor and had the keypad locked out, I set mine up to take an average of all floors as the controlling set point.  sorry dont know part #   check with controlco in San Fran.  415-647-9445.


@ December 7, 2012 11:21 AM in pumps

2-  grundfoss  UP-26-99BF bronze pumps   unused in boxes less than 2 yrs old    make offer     in the Sacramento CA area

natural gas chart

@ December 6, 2012 12:36 PM in Something new.

here is the sizing chart


@ December 6, 2012 11:37 AM in Something new.

I have a good chart for figuring nat. gas pipe sizes   let me know if you need one.


@ December 6, 2012 11:32 AM in Something new.

How do you get to bookmarked threads     might be my laptop

taco wiring

@ December 4, 2012 4:35 PM in thermostat does not start boiler

the fastest way to solve this would be for you to go on yahoo and type in taco zone valve wiring  there are numerous schematics etc, make sure your wiring is correct and connections tight.  Be careful disconnecting the 3 wire actuators, before taking off of the valve body disconnect the 24volts for about 5 minutes These old valves had a heat motor  read caution notes


@ December 3, 2012 8:17 PM in Honeywell M9185D 1004 Modutrol

forgot to say that when testing actuator external wires on r.w.b  terminals should be  removed , only 24v wiring hooked up.  also t991a is a modulating temp. control.  i recommend that you install a manual potentiometer to test motor,  honeywell makes one, not sure of part no.


@ December 3, 2012 7:10 PM in Honeywell M9185D 1004 Modutrol

This is a series 90 actuator (135 ohm )   testing should be done with actuator disconnected from valve linkage.  r-b opens valve like you did,  jumpering r-w should close valve (rotate the opposite way)   or  install potentiometer per instructions rotating dial on t991a will add or take away resistance to motor circut,  If motor does'nt move and there is no voltage drop to your 24 volt supply I would recheck all connections, If this does'nt work I would replace it, not alot to troubleshoot on inner motor workings,  make sure your valve is not bound up which is the biggest cause of actuator failure   You might consider replacing the valve,actuator and linkage        contact    for additional info

water feeder

@ December 3, 2012 4:59 PM in Very busy and loud feed water solenoid

You can install a press reducing valve ahead of the water feeder.   Bell & Gosset B7, or watts makes several types

primary secondary

@ December 1, 2012 6:37 PM in Unwanted reverse flow between tees

In most commercial systems Tel. Larrs, bell&gosset the primary loop (system loop) travels around the bldg to the individual terminals, the primary (system loop) includes the expansion tank, main pump,and air seperator. The secondary loop is usually where the tees take off and where the boiler is piped into. the secondary loop adds heat to the secondary as needed.  The terminology is often flip flopped in residential and light commercial radiant systems calling the primary-secondary and vise versa. the individual radiant zones can be there own secondary loop off the primary loop with there own pumps,  once again drawing would help  also have pumps been sized forTEL and or press drop of system.


@ December 1, 2012 4:46 PM in Unwanted reverse flow between tees

send a detailed piping drawing and we can get to the bottom of this  Taco has a website that used to have some good radiant heat info.  Usually the boiler is on the secondary loop.


@ November 30, 2012 2:43 PM in Combustion analyzes

I always liked the Testo brand  I think it was the 325 mod. which came with a printer  needs to read nox       
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