Replacement gas boiler questions- in the planning phase.

zmcgarvey

Hey, new member here, first post. I live in a 1940 brick rancher, 1450 sq ft, in southern New Jersey with a simple hot water heat system. It's a single zone with 1 or 2 tube-and-fin convectors in each room and currently does an adequate job heating the house. I am replacing my circa 1975 W-M gas boiler (105k BTU input) with a new one basically as preventative maintenance and have a few questions. Hoping you can help. I've read up extensively on hydronic heating science and I'm looking to make my installation as perfect and trouble free as possible.

1. I want to buy a standard efficiency atmospheric boiler as I value simplicity and reliability over efficiency. I am looking at Weil-Mclain CGAs and Williamson-Thermoflo WGAs, and to me they look identical but for their external appearance. The Williamson is almost $300 cheaper than the W-M. If they are truly exactly the same and someone can confirm, I'd rather save the money on the boiler and spend it on really nice trim parts. Below are links to their respective manuals for reference. Even the drawings and most of the replacement part numbers look the same.

http://www.weil-mclain.com/sites/default/files/field-file/CGa Series 2 Boiler Manual 1016 Web Version - Starting CP7540456.pdf

http://www.williamson-thermoflo.com/sites/default/files/field-file/gwa_manual (1).pdf

2. Obviously my current boiler is grossly oversized and I want to fix this. I calculated my heat loss (actually my gas consumption, since I clocked the meter) over a 3 day period of 15 degree temperatures at an average of around 26k BTUs per hour. This was with the thermostat set to 62, where I normally keep it. I would like to install the smallest boiler possible for the application but I want to have the option to maintain high 60s in design conditions, which around here is probably closer to zero degrees. Does anyone have any idea what this would extrapolate to? Would a 38k (IBR) rated boiler like a W-M CGA-25 do the job? Or is a CGA-3 51k or equivalent a safer bet?

3. One thing that scares me about these boiler models is the motorized vent damper as a potential reliability issue. I know it's been discussed to death and the manufacturer wants the unit installed with it in. I'm planning on doing so, but should it ever fail and I need to temporarily remove it and jump out the control, how is this done? In the W-M manual I see a 4-pin connector for the damper- I assume 2 wires are hot and neutral to the motor and 2 are for a position switch, but they aren't identified as which is which. Any rule of thumb here? Is it more obvious when I have the unit in front of me? Just trying to be prepared.

Thanks for the help. I'm going to start ripping out my old equipment soon and I'll be looking forward to any advice.

Zach in NJ

Rich_49

Zach ,

Where in Jersey are you exactly ?
Either of those boilers would be fine and you may even want to check out Ferguson's Force boiler made by either Peerless or Burnham , not exactly sure which .

I would keep a spare damper available just in case , not that expensive .

I would certainly perform a room by room heat loss and the see what water temps are required based on the installed baseboard .

Seeing as you have a ranch house also there is quite the opportunity to run homeruns to all the rooms so that all baseboard receives same water temps . Small investment , big comfort gain , all rooms comfortable . Later on in life if you want to zone it out taht becomes way easy also . A couple actuators and a small zone control module and you're done .

zmcgarvey

Gloucester County. Directly across the river from the Philly airport.

My current piping situation works well and all rooms are comfortable, I really have no need to change it. I'm only replacing the boiler due to age, everything works fine. I have been there approximately 10 years and have done everything possible to improve insulation and air infiltration, but there is only so much one can do on a masonry constructed house without cavity walls. I have played around with various heat loss calculators and they all came up in the vicinity of 30k to 40k/hr. I'm mainly worried that on very cold days I'll come up short with a 38k output. I want to be able to occasionally "splurge" and heat the house to 68 or so if we have company that isn't used to being cold in the house . Normally the stat stays at 62!

Steamhead

When looking at boiler output ratings, did you use the DOE or Net output figures?

The Net ratings include a pick-up factor that allows for the extra heat needed to warm up the pipes, convectors etc. in the system. This allows the system to recover reasonably quickly in case of a power failure or if you set the thermostat back at night.

JUGHNE

Years ago I could tolerate a low 60's house......today it is a low 70's for comfort to me........something changed.

I would go for the inside design temp of 70 in heat calculations.
Not only for the ageing process, but as you said company, setback recovery etc. Also resale value.....most people will feel cold touring your 62 degree house.....so I would pump up the temp for the viewing......in addition to "the freshly baked cookie spray" (does someone actually make that product?)

zmcgarvey

Those were net ibr outputs, steamhead. With an indoor design temp of 70, outdoor of 5, I'm somewhere around 40k per hour. I'm leaning towards the 51k output unit.

Anyone know anything about the Williamson brand? Is it really the exact same thing as a W-M? If there is anything at all to be gained I'll pay the extra money for the name brand. Otherwise I'll just stick with the Williamson. I just want to be sure I'm not sacrificing quality or reliability over a few hundred bucks.

EBEBRATT-Ed

First of all you may sell the house some day so it's best to not undersize the boiler. Slant Finn has a accurate heat loss calculator which I believe you can download. ( I have and old copy on a disk) so do an accurate heat loss. The boiler manufactures build a 15% piping and pick up factor into their ratings.

As far as I know Williamson and Weil McLain are the same boiler. The vent dampers and controls are pretty reliable but you could stock a few extra parts an ignitor is usually the first item to fail. When I started writing this there were no other posts. Guess my fingers are getting slow!!!!! Everyone has about the same advise

Well that's weird!!! I didn't see any other posts but I guess they were there????

zmcgarvey

The two heat loss calculators I've been using are those on Slantfin's and Burnhams websites. I believe my air infiltration to be fairly low, but the R-value of brick and plaster is also very low. The only insulation in my house is in the stick framed addition I built, and the several layers of fiberglass batts I installed on the attic floor (around R-30, give or take). As stated I will go with the 51k boiler since I'm coming up just slightly above the 38k output of the next size down.

If I can be certain the WM and Williamson boilers are exactly the same and use the same replacement parts I'll go with the cheaper one and spend the savings on a Spirovent and lots of new ball valves to isolate various components for future service. Also a new Watts 9D and a nice feed valve (any suggestions?)

Bob Bona_4

Good plan with doing quality near boiler components. If possible, mount the stuff on a wall, as a package, and only have a supply and return going to new boiler. Pump away. Feed at expansion tank.

hot_rod

A boiler trim kit is the way to go, here is one of the best
Caleffi NA 553

Rich_49

hot rod said:

A boiler trim kit is the way to go, here is one of the best
Caleffi NA 553

Very good investment here . We use them quite often .

bob eck

Check out the Advantage cast iron boilers at
Pureproproducts.com from F W Webb
We have a store in Allentown PA 484-488-3669 have your local heating professional contractor call us.
Advantage boiler is built by US Boiler (Burnham Boiler)
Some states and local gas utilities offer rebates for high efficiency gas boiler check it out.

zmcgarvey

Thanks for the advice. I'll buy one of those boiler trim kits you suggested. I will also stick with the 51k boiler- who knows, in 25 years I'll be in my 50s and may have different opinions on what a comfortable temperature is.

One more question. I'm planning on piping my boiler like this: Return pipe from house --> expansion tank --> boiler --> circulator ---> spirovent ---> supply pipe to house.

This way I will be pumping away from the expansion tank. Will the spirovent work well on the discharge side of the circulator? I want to keep it on the hot side of the system.

JUGHNE

You need more info concerning "pumping away". I believe all those components you mentioned should go on the supply side of the boiler.
Caleffi has a series of books that should cover this piping.
Also the bookstore here may have a copy of "Pumping Away" by Dan.
Don't skimp on isolation valves that allow you to service components between the supply and return piping, also purging air.

Note: IIWM I would get both books.

Rich_49

zmcgarvey said:

Thanks for the advice. I'll buy one of those boiler trim kits you suggested. I will also stick with the 51k boiler- who knows, in 25 years I'll be in my 50s and may have different opinions on what a comfortable temperature is.

One more question. I'm planning on piping my boiler like this: Return pipe from house --> expansion tank --> boiler --> circulator ---> spirovent ---> supply pipe to house.

This way I will be pumping away from the expansion tank. Will the spirovent work well on the discharge side of the circulator? I want to keep it on the hot side of the system.

Ready ? Boiler , Supply , Caleffi Air eliminator , make up water and expansion tank connected to bottom port of air eliminator , Circ , all piping , return to boiler . Done and Done

zmcgarvey

Been a few months, but I made some progress. Thanks to everyone who contributed advice. I still need to mount and connect my expansion tank. I will be using a hydroclaw x-tank bracket from Storm King Enterprises (http://www.supplyhouse.com/Storm-King-Enterprises-HC11-A-11-HydroClaw-Expansion-Tank-Support-Bracket).

I designed my piping for future serviceability, the return goes around the back and out of the way, and the supply has a union a few inches above the outlet that will allow the top of the boiler jacket to be removed without taking everything apart. I used a Webstone pro-pal purge valve and isolation flanges on both sides of the circulator. Now I just hope I don't have any leaks in my solder joints when I fill this thing up! I will post again later in the summer with an update.

http://imgur.com/a/Gbt0H

zmcgarvey

Made a few notes in the picture for clarification. The markup is what is yet to be installed.

Wardo

Can you tell us about the chimney & fresh air supply? Is that silver foil tape on the exhaust vent?

Zman

The expansion tank setup looks good. If you put the bleeder above the valve, it will make replacing the expansion tank a snap.

hot_rod

The circulator should be mounted with the motor horizontal, loosen the flanges and turn it 1/4 turn.

HVACNUT

> @hot rod said:
> The circulator should be mounted with the motor horizontal, loosen the flanges and turn it 1/4 turn.

>> the motor is on the horizontal. I had to zoom in to see it. Like my friend Kurt used to say, "Its an optical illusion".
Am I missing something? The supply tee's off, run to supply space heat, and run back to the boiler. Where's the return from the space heat, or am I not looking st this right?
Also, did you use 1/2" screws on the draft damper connection? Sometimes the damper hangs up on the screws.

zmcgarvey

I think my picture may have given a few wrong impressions, but I nevertheless appreciate the advice and criticism! To answer the above:

1.The circulator motor is horizontal, as specified by Taco.

2. The supply does not tee off, the 1" copper comes off the circ pump and runs into the house. The other pipe you see is the return, about 6" below it. For whatever reason the picture makes it look like they connect, but they only overlap! The return runs below it and then to the rear of the boiler, and finally to the return tapping on the left side. One zone only for all rooms, piped in a parallel circuit, so-to-speak.

3. The draft damper sheet metal screws are very small, not sure on the size, but the heads are 1/4" hex. Definitely no interference.

4. The chimney is a 6" stainless steel liner dropped down a masonry chase. Yes, there is currently foil tape on the flue pipe, it's only there as a temporary measure until I find a better transition fitting. I won't be relying on it in operation. I just wanted to make it harder for bugs and stuff to get in there right now.

Now a few questions-

1. Do I need to worry much about air accumulating the the long vertical expansion tank pipe? Does it even matter if it does?
2. When I fire it up in the fall, will adjustment of the Honeywell gas valve be necessary? I believe it has an adjustment screw and an output pressure tap. Are these things good to go out of the box, or should I buy a gas manometer and double check it? Is it worth having someone come out and put a combustion analyzer on it?

Jamie Hall

Question 1 -- no. Nothing to worry about. Won't make a bit of difference.

Question 2. The valve might not need adjustment -- but I wouldn't count on it. I'd get someone competent to come out with the proper gadgetry and get it really set right.

zmcgarvey

Got the last of the piping done and filled it up. I'm pressure testing it right now with the expansion tank isolation valve to "stress test" everything at just below the relief valve pressure. In operation I'll only be running 12psi, but I just want to give anything that's going to leak, a chance to leak now in July!

Here are a few pictures of the progress. Pretty much all that remains is to let a little pressure out and fire it up.

zmcgarvey

I had an issue where, upon filling the system, the right hand circulator flange threads leaked (about two drips per second). I loosened the flanges and backed the threads off, applied some teflon tape, and retightened. Thankfully, no solder joints leaked. I was careful and used Staybrite 8 which is a high strength solder that is way overkill for the application. It sure flows nice and I recommend it to anyone who is frustrated with the working properties of lead-free solder. I use it for everything, including on refrigerant applications where brazing alloy is normally called for, and I haven't had a failure, even on R410A.

Next step is to adjust the gas valve output pressure and get someone in here who has a combustion analyzer to check it. Heaters normally don't get turned on until after Halloween around here so it's unlikely that I'll do anything more with this project for a while.

Thanks for the advice and any criticism is welcome, I'll be checking back here from time to time.

JUGHNE

Is your water heater T&P relief valve and the boiler relief valve connected together with PVC pipe? I do believe that is usually not done without an air gap between each.

And not with PVC which could melt shut.

zmcgarvey

Yes they are. Are you concerned about boiler water blowing back into the water heater? If so that's impossible, as the boiler relief vents at 30psi and the relief valve for DHW at much higher- 150psi. I don't see any danger here. They both dump into a properly pitched drain that runs outdoors into a location that is easily monitored for leakage. It seems to me that this is much better that the more common "let it drip on the floor" approach. If someone can tell me a good reason I will change it.

HVACNUT

Maybe others can chime in, but I believe that's a code violation with the relief valves tee'd together.

hot_rod

Check with codes in your area. Typically PVC is not allowed, possibly CPVC. Teeing two relief discharges is not usually allowed either.

Here are a few opinions from manufacturers, plumbers and inspectors.

http://www.oconomowocplumbing.com/design/wisconsin-plumbing-code-water-heater-relief-valve/

zmcgarvey

I'll redo it with two separate drains, and I'll probably use pex since CPVC isn't really available around here. I don't want to use copper pipe because if I have to change out a pressure relief valve in the future, I'd like it to be a simple operation to cut the pipe and reattach it. Not enough clearance back there for a union.

Zman

Where does the pvc go? Hopefully there is an air gap before a drain.

I don't see the issue with a union at the valve in either case. You could pick up a shark bite coupler and removal tool if space is a concern.

Regardless of what the code says, look at the melting point of the materials being used. If the boiler runs away on high temp and blows the 30 psi relief, the temp of that water will be about 275 degrees.Don't forget it will be flashing to steam and rapidly expanding. A copper or steel pipe would be better...

hot_rod

A 3/4 MIP by compression adapter is a slick way to adapt into a T&P, or relief valve. It allows for easy removal.

A 3/4 MIP shark bite would work, possibly not rated for potential relief temperatures.

With some practice a channel locks can be used to release shark fittings, just need to slide the collar back.

JUGHNE

You could use 3/4" black drop pipes for each. Just hang them into a larger pipe (1 1/4- 1 1/2) so they maintain an air gap to allow overflow if they open for a serious issue and your outside drain is frozen shut or has something living inside with a very tight nest construction. Even 1 1/2" PVC pipe on the floor with that air gap would be a better situation. You could flush each yearly to check their sealing/flushing ability without flooding the floor. And any dripping would go out your wall drain pipe. IMO

zmcgarvey

Probably will use 3/4" pex (have some 10' sticks and fittings left over from a previous project) and a sharkbite at each relief valve as a union. Hate those things but I guess this time it will actually make life easier.

And yes, there is an air gap between the relief piping and the drain. It isn't a real drain anyway, just a pipe that goes through the masonry wall and outside.

The only reason I even have this in place rather than the code-minimum short piece terminating near the floor, is that I like to test and operate those valves once in a while. We all know that with valves, if you don't use it, you lose it-- or at least they never seal again.

zmcgarvey

Just wanted to update this forum now that my new boiler is in operation- all is well and I appreciate all the advice I got back in the summer. I did end up ripping out that PVC drain and redoing it with black pipe, along with an air gap to meet code requirements and to allow easy indoor inspection for any dripping.

Fired it up around the first of November and it worked great. The first 15 minutes or so was all it took to get the air out of the system. I highly recommend the Honeywell Supervent as an alternative to the more expensive Spirovent. It has a knurled cap which allows the top to be removed by hand for inspection or cleaning in case the valve seat starts to get crusty.