Need help decision making on a boiler...

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Old 08-11-14, 03:56 PM
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Need help decision making on a boiler...

Hi guys, and thanks in advance for looking at my question.

As my name implies, I have no idea what I'm doing when it comes to boilers, but I am trying to rapidly learn before winter

So the situation: My boiler started jackhammering and no matter how much I attempted to purge the system, it did not seem to make a difference. Called a boiler company and they concluded the jackets in the boiler were likely crusted over with lime causing the jackhammering.. I suppose this is possible, since the unit is a 1959 Bryant 100,000 btu boiler.

The expansion tank is an open style (water with air, no bladder) and hangs in the rafters.. It is about half full of air and water. System has a manual fill valve (scary but works and is running at 12 pounds when hot. No backflow or other current code parts, so all of this will have to be revamped.

The boiler guys wanted to install a Weil McLain unit of similar rating (80% efficiency) for around 5000.00 dollars. This includes revamping the expansion tank, adding an air scoop, probably doing some code things like an auto filler and anti backflow valve and such..

Problem is, I have about 1000.00 and can probably at best muster 2000 more by begging, borrowing etc.. So I am stuck doing it myself, if in fact this seems to be the issue.

Looking around I came across the Navien NCB combi boilers, and I like the idea of replacing my inefficient 40 gal water heater and ancient boiler with one of these. I can probably get one for about 2400 shipped online, and because it handles the pressure regulation on the boiler, I would only likely need the air scoop, expansion tank, condensate filter (I have cast plumbing) and backflow valve as well as the servicing valves for convenience.. I will likely get my water tested for minerals as well, and get the proper filters to handle those too. I plan to get an outdoor temperature sensor for the unit as well and just use a wireless remote.

OK so some more specs before the questions start...

House is about 2100 square feet and is a single zone with 1 inch pipes that split somewhere to 3/4 pipes and then come back to 1 inch piping.. Location is South Dakota which can get very crispy in the wintertime. Some Januarys never see a day above 0 degrees F.

Plan is to cut out the old boiler and put in the new one, making a primary loop with close t connections all in 1 inch tubing so that the piping can mostly be reused including the pump if possible. Pump specs are unknown, and if this is considered cheaping out, I'm happy to replace it too..

I do have the feet of the radiators as well if this is helpful, but their manufacture is unknown.. 91.333- feet or 1096 inches total radiator length. BTU loss in the house is about 77,500 btu / h as calculated by Slant/Fin at 0 degrees and 180 temp (which, if I can, I'd like to run at 165 so I can get the benefit of condensing). As I have heard there are limitations to combi boilers flow-wise (4.5gpm on the primary loop), I am planning on going to the ncb-240, even though technically it is "too big" for my heat loss, since it is a modulating unit and I'd rather have the margin and sacrifice the .3% efficiency over the NCB-210. I'll also get some margin on the hot water.

First, is this a doable project for a novice like me, or am I better off just going with a Weil Mcclain unit of around 100,000 btu and 80% and being done with it? The project has to be done by me, and it will take a lot of time at 10-13 % increased efficiency to burn up the 2500 dollars I save doing it myself over having someone else do it. If I use the Navien, I plan to use CPVC for intake and exhaust to handle 180 degrees if necessary and this will be routed directly out the basement wall instead of up the chimney like the current unit. If I use a conventional unit, it will go where the current one is. I plan to be well within code on the exhaust system, and will probably have a CO detector installed to be sure all is well..

If this is a doable project as I've laid it out and is appropriate, what have I missed? Quite frankly, where do I even begin? Will I likely get enough temp drop in the pipe for the unit to condense, or am I wasting my time with one zone? Will the last rooms be too cold with this much pipe if it does get to condensing temps? Is it better if I split the zone into roughly 2 segments? I could do an upstairs and downstairs zone, (drop roof ceiling in basement) but I am running out of summertime quickly. As I have previously stated, I know nothing about boilers, so any helpful direction is appreciated but please be kind.. I'm a newb.


Thanks again!
 
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Old 08-11-14, 05:14 PM
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First off, define your understanding of 'jackhammering'.

Describe the symptoms... when does it start, when does it stop, boiler cold? hot? etc etc...

I'm always for fixing something rather than replacing.

I presume this is natural gas fired?
 
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Old 08-11-14, 05:17 PM
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running at 12 pounds when hot
What is the pressure when COLD?

You should run at 12 PSI when COLD... when HOT the pressure should be higher, but at this point that's simply informational as it won't change the outcome of your decision.
 
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Old 08-11-14, 05:22 PM
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condensate filter
What do you mean by 'condensate' ?

If this is in fact a hot water system and NOT a STEAM system, you won't have 'condensate'.

I think you mean a filter on the RETURN WATER to the boiler to keep the 'crud' out of the boiler, right?

(I have cast plumbing)
I'm sure that you mean BLACK STEEL, right?
 
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Old 08-11-14, 05:29 PM
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(which, if I can, I'd like to run at 165 so I can get the benefit of condensing)
You probably won't be condensing at 165 unless you have more than a 30F delta T (difference between supply and return water). In order for a condensing boiler to condense, the return water must be below 135F.

Depending on how many radiators (BTUH of heat emitters) you have in the home as opposed to the heat loss, you might not be able to heat the home with 165F water... at least in January anyway... and perhaps in SD November, December and February. You might condense in Sept, Oct?, and March.
 
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Old 08-11-14, 05:33 PM
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is this a doable project for a novice like me
What is your 'skill set' ?

You'll be biting off a big piece of meat. What happens if you get into it and realize that for some reason you can't chew and swallow? What do you do then?

My intent is not to discourage, rather to make sure that you don't get in too deep.

Clint Eastwood said:

"A man's got to know his limitations."

Make sure you know yours!
 

Last edited by NJT; 08-11-14 at 05:54 PM.
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Old 08-12-14, 09:37 AM
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Hey NJtrooper, thanks for your replies.

To answer the jackhammering question, basically when the boiler is fired (it is natural gas) all will be quiet for about 10 to 15 minutes aside from the slight hum of the pump which is barely audible.. Then, before it even gets hot, there starts to be a banging in the pipes, nearish to the boiler or probably inside it. When the boiler was operational, the pressure would hover between 12psi when cold and 14-16 psi when hot.. I only once had the pressure valve pop on it, and that was because I added cold water while it was hot, which was very stupid, I know. The result was a blast out the relief valve and then pressure was normalized quickly. I have now 5 years of working with this boiler, so I am much wiser to how this thing works than when I first moved in. When it bangs, it does not seem to be sufficient to pop the valve, but man it sounds like an explosion is going on over and over from upstairs.

When the system is low or has air in it, I can tell because it bubbles or gurgles in the lines, even when cold. I am not getting any of that now, so I am pretty sure there is no air in the lines.

By condensate filter, I mean the Navien I plan to use is a condensing unit and that the runoff or condensate which is acidic needs to be neutralized before going into my cast plumbing.. that may change in the future, but for now my drains are cast iron. There is very little steel pipe in the boiler itself- just one pipe about 2.5 inches that comes out of the top of the unit and then splits to a 1 inch copper line and then a maybe 1/4 inch line for the expansion tank off the top- I suppose a 1960 equivalent of an air scoop but it is basically an L fitting with a 2.5 inch inlet, 1 inch 90 degree outlet and 1/4 inch outlet at the top of the L (so it is a T, but the 1/4 outlet just catches the bubbles). This piece of steel pipe I plan to remove when the new boiler is installed.

As far as technical aptitude, I feel fairly confident about installing a non-condensing boiler, since it is an R&R job, plus a few code items- I'm not afraid to sweat pipes, and boilers run at a much lower pressure than regular plumbing so I'm not worried about that. Also, 100,000 BTU at 80 percent efficiency worked well in my house, so if I were to replace it, the bill would effectively be what I'm used to paying (even if they oversized it), since nothing changed. Basically the math right or wrong has already been done and I'm used to paying it.. About the only thing that would need to be changed would be wiring the unit, which I am fairly comfortable with wiring up things as well.

The Navien on the other hand, would require I make sure it is sized properly, since it is a totally different kind of boiler, so it doesn't have jackets that hold in the heat as well, etc, and it requires the primary, secondary loop, etc.. there's just a lot going on when it goes to sizing it.

I basically have nothing to loose with the conventional heater as I think it will work and if I do get stuck on something, well, I pay for that part to be unstuck for me and I've done 80 percent of the labor already- I pay just for the labor- Maybe 300 or so instead of 3000-3500 for the labor and parts over what I can do myself. I think I've done enough research to know all the parts I would need code-wise, and I know about installing safety valves and cleaning t's etc.. Regardless of the boiler installed, I want it to be easily serviceable. Without a doubt, I can certainly appreciate your concern as far as my limitations- most homeowners should not even attempt a boiler install- I get that. I am definitely not too proud to have someone help me where there is a snag or two but I want to be able to save where I can. I would like to say that I have a pretty good handle on my limitations, but as you can see, I'm right on the ragged edge as far as condensing boilers go, so I'm looking for knowledgeable advice and suggestions.

Where I am positive I lack the skill is just getting this thing sized right- I definitely do not want to be cold this winter, and I'm not sure I fully understand how condensing boilers work.. I know there needs to be significant delta-t in order for them to condense, and therefore to work and I know that the boiler output temps need to be 165, not 180 in order to do so, I'm just worried that by the time I get that delta-t to condense, the last few rooms will be iceboxes, lol.. Also, I don't even know what flow I need to keep the water in the rads long enough to dump their heat and return, so this is where I have concerns.. Probably the biggest concern is that even if I do run this thing at 180 that it underperforms and I end up having to buy a different boiler anyway- THAT would be a disaster.

Anyway, I really appreciate your input and I hope that answers most of your questions.
 
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Old 08-12-14, 04:53 PM
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Since the boiler is from '59 you said, it might be time to replace, but since you are on a tight budget, why not first try to run a cleaner in the system and see what happens?

The "Hydro-Solv 9100" has been used with success by a couple members for this issue.

For $50 bucks, if you can get more time out of the old gal, why not?

Rhomar Boiler Chemical Treatment and Test Kit - 83287
 
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Old 08-12-14, 05:09 PM
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condensate which is acidic needs to be neutralized
After I posted my question I realized you might be talking about the flue gas condensate, and yes, you most definitely would want to neutralize that before dumping in a drain. Neutralizers are easy to build and use 'marble chips' that you can buy cheaply at the home stores as 'fuel'. Or, you can buy a pre-made unit.

Regardless of the boiler installed, I want it to be easily serviceable
For what it's worth, I'm not a fan of using a 'water heater' to heat a home. IMHO, if you want to go with a mod/con, the Triangle Tube would be the way to go, but they are pricey.

And " ... easily serviceable ... " , well, I don't think I would call the Navien that.

I don't think you'll be real happy with the domestic hot water either, but like I said, these are just opinions, and some people are happy with theirs.

Google " cold water sandwich " for more info. I know that Navien claims they've solved that issue but my O is that it's marketing hype.

Based on your description of your system, I don't think I would recommend a mod/con.

Don't forget that you'll be paying several hundred a year for the annual REQUIRED maintenance!

I know there needs to be significant delta-t in order for them to condense, and therefore to work and I know that the boiler output temps need to be 165, not 180 in order to do so, I'm just worried that by the time I get that delta-t to condense, the last few rooms will be iceboxes,
It's not exactly and directly the boiler OUTPUT that needs to be lower temps, it's the water that RETURNS from your radiators that does.

Let's say that the return water comes back 20F COOLER than your supply temp going out. This means that the TOP END of the temp for condensing is going to need to be no more than 155F. A portion of the winter you may be able to heat the home with that temp water, but as soon as the weather gets real cold, the condensing boilers STOP condensing, and at that point you are back at the same efficiency as a standard boiler.

In order to get the benefit of a condensing boiler through the entire winter, one would need to install MUCH MORE radiators in order to get the BTU output to heat the home with cooler water in the cold parts of the winter.

Try the cleaner first and see what happens.
 
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Old 08-12-14, 06:06 PM
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Those compact wall-hanging units are popular in Asia and in Europe where DIY is relatively unheard of, if not prohibited - and people live in very tight quarters. Owners call the factory for service, and a nattily dressed, uniformed serviceman shows up. The U.S. market is a bit different.
 
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Old 08-13-14, 04:36 AM
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Originally Posted by NJ Trooper
". . . Since the boiler is from '59 you said, it might be time to replace, but since you are on a tight budget, why not first try to run a cleaner in the system and see what happens? . . ."
I'll endorse Troopers suggestion; as many times I've heard the suggestion that I replace my boiler.

I have an old John Woods boiler, probably from well before 1959; but it's steel, and over the past 27 years, I've slowly replaced most, if not all, of the "moving parts": the Burner; Circulator; Aquastat; Feed Valve; Expansion Tank; Damper; Pressure Relief Valve; Air Scoop; Flow-Check; even the Oil Tank . . . . plus a few more minor gadgets that I can't think of at the moment. And now, all that I have left which is original . . . . is the Firebox/Combustion Chamber (and the DHW Coil).

My Boiler is now like an Old Friend, with whom I've become intimately acquainted. I wouldn't want something new and un-predictable.
 
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Old 08-13-14, 07:55 AM
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The "Hydro-Solv 9100" has been used with success by a couple members for this issue.

For $50 bucks, if you can get more time out of the old gal, why not?

Rhomar Boiler Chemical Treatment and Test Kit - 83287
FWIW - Hydro-Solv 9100 completely solved my kettling issue. That kit is rather small, I purchased a gallon of each, cleaner and treatment after a call to the mfg. Run it in the system for a good month during the heating season and give it a good flush. Then use the treatment/conditioner with your new fill.
 
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Old 08-13-14, 05:04 PM
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Thanks so much for all of your replies.. I am definately going to give the Hydro-solv 9100 a try first..

So the next question I have is, How the heck do I get it in there? This boiler has no servicing ports at all, just a water valve going straight into the boiler- not even a pressure regulator or a backflow valve! Do I just cut in a service port since I should likely drain it anyway and then fill it up? With an open air expansion tank, should I just open that up too, drain the whole system, add the solvent and then fill the unit until water comes out of the tank and then close it up and let it fill about half way? There is so little info on how to fill these old Bournemouths.. Should I delete it and put an air scoop on it so it can vent and get a closed-style expansion tank? I could definitely figure out how to service it then.. I just don't want to do too much in case I have to tear it out anyway.

Thanks again guys, You've been very helpful so far.. :O)
 
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Old 08-13-14, 05:19 PM
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You could drain the boiler water level below the level of the relief valve. Remove the relief valve, and pour in the cleaner.
 
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Old 08-13-14, 05:41 PM
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Yes, usually the pressure relief valve, there has to be one...

Can you take and post some pics of your boiler and all the piping around it? We'll be better able to help you that way.

The less you have to drain, the better.
 
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