Pipe plug "fixes" leaking PRV

JUGHNE

Call was for 80+ year old dripping CI radiator; only leaked during heating season.

No, we can't take it apart to fix nor easily buy a new one.  Go for a look at the boiler and of course the pressure gauge is shot, sitting stuck on 40 PSI.  Look to open the PRV and find a 1/2" pipe plug in the bottom drain opening!!  It is a 3 year old B&G combo fast fill & PRV.  So the eventually the storey comes out;  3 years ago something dripping/leaking in bsmt--local HVAC guy looks at it & orders new--helper comes to install later--all is good--lady calls him back 30 minutes later--something still leaking--helper fixes leak with 1/2" ips plug and all is good again. 3 years later radiator leaking. Jump to yesterday: remove plug, drain 1 gal water, pressure drops to 16 PSI ,gauge was actually good, fire boiler: pressure up to 25 psi in 30 seconds--of course compression tank completely waterlogged.  HO says that gauge pegs out over 80 psi in the winter time.  I think their Angels are with them all the time and gave the warning at the leaking kitchen radiator.

Boiler is Bryant 8W-26 C LG (now NG) SN 21177 180,000 BTUH.  Surprised by Install book being inside cabinet "effective 7-1-54".

100 year old house, gravity piping, all CI radiation, had pump added with this boiler.  Of course could just do a cleaning, get air in the tank, flush out boiler, (probably never done in 60 years)  and leave out the pipe plug!!

HO show interest in higher efficiency, I don't believe condensing unit justified for this CI system.  The only item I'm uncomfortable with is the Gas Train----Basco valve with t-couple pilot--Bryant Diaphragm main gas valve (1/2 A634 SN:9KT) -- adjustable water temp control limit control (not electric) "Titan T-43-B" which has 1/4" Al tubing to act on the diaphragm of main valve.  It does light off nicely though.

Any suggestions--total replace--clean w/new gas train.  Thanks! JUGNE

Steamhead

First thing to do

is a heat-loss calculation. Then you know what size boiler is actually needed, and can explore options.



As for the previous guy- YOU CAN'T FIX STUPID!

kcopp

the other one....

I have seen is another prv valve stuck inside the outlet  of the leaking prv....

The Steam Whisperer (Formerly Boilerpro)

Or another...

The PRV was installed backwards.  I guess the tech didn't have a 3/4 coupling to install the male end of the relief valve on the end of the pipe.

JUGHNE

Heat loss calculation for pipe plug job

Steam-head:  my best shot on heat loss is 113,000 one method; 110,00 2ND method.

House is 1156 sq ft. block wall, lath, plaster.  1 1/2 story--shed dormers--knee walls etc.  (tough for accurate measurements on 2 ND floor.) One tends to over calculate heat loss in this case.

However there are 9 CI radiators connected adding up to 359.5 EDR. Even at 200 BTUH (195 * water) this is 71,900 BTUH.  add 25% equals 89,875 BTUH.

(This was originally gravity system, 2" pipes w/2 risers.)

HO says they have always been comfortable (-7 degree ODT).

Mod Con looks to be best replacement, unlined masonry chimney has issues nearing the end of it's 100 year life, (bad mortar above roof).

Would anyone recommend Mod Con with 105,000 input/95,000 max btu/hr output 5:1 turn down or size up to 150,000/136,000 max out. 5:1 turn down.

Which would give the best condensing/efficiency?

Existing circ pump pushing thru old boiler is Grundfos UPS-15-42 F.

Would it work for system pump on primary/secondary set up?  It is obviously moving enough water even with the 8 section CI boiler in circuit.  (boiler pump would be furnished with Mod Con unit)

Thanks,  JUGNE

Steamhead

I'd re-check your heat loss and rad measurements

something isn't adding up here.



Is there a safe place to vent a mod-con?

Mark Eatherton

I'm with Steamhead...

I've never seen a loss calc, even in an older home, greater than 50 btu/sq ft/hour. You're at 97 btu/sq ft/hr.



Don't use THE coldest temperature you've ever seen. Use the "design" temperature for your area. The house has enough internal mass to carry you through the dips below design conditions.



Recheck your math.



ME

JUGHNE

Boiler sizing

A little tweaking of numbers put the heat loss at 95,558 BTU.  Outside design temp used was -7. (We are in 7070 heating degree day area) This house has windows/doors as 18% of gross wall area.  Windows are original double hung with pulleys & weights.  So-so storm windows. 1 1/2 air changes assumed. EDR counts of height, columns, and sections figured 3 times from 2 different books with same results.  5 rad downstairs, 4 rad upstairs.

There is good Mod Con side wall venting available.  I know this is a backasswords way to size a boiler.  My logic is that if I could at least supply the BTU for the EDR available and rely on turn down modulation for shoulder seasons. So looking at the 105,000 in/95,000out.  Next smaller size is 80,000 in/73,000out. Always seeking good advice.  Any ideas on the pump question? Thanks again, JUGNE 

kcopp

personally.....

I like the Smith g160. It has the 5.1 turn-down, you can turn down the boiler output to 30k. stainless steel HX, wall hung, concentric vent w/ PP. Able to vent 100', even up an old chimney. For a pump I am thinking small... 15-58 on low spd. or a 005.

http://www.smithboiler.com/html/gc160-condensing-boiler.asp