Amateur DIY hot water boiler install on old gravity system with steam boiler attached (long story..)

gchrisman

After last years heating saga at my house (details and photos here: https://forum.heatinghelp.com/discussion/185457/trying-to-understand-old-two-pipe-steam-system/p1), I am entering summer with no changes to the heating system from last year. Over the winter, the (completely incorrect) steam boiler barely kept things from freezing, at spectacular cost in propane. I had two separate contractors come out, look things over, and say they would get back to me with quotes - months have gone by, I've bugged them many times, and no quotes are forthcoming. One guy finally said that he just didn't have time for my job, and the other won't answer my calls or emails at all. Between the original debacle and this sort of apathy, I am giving up on getting any help from the professionals in my area. I need this system to work by next winter, and I think the only way to do it is going to be to do it myself.

I'm a fairly handy guy, but have no experience working with boilers. I've read the long FAQ here about gravity system conversions, and I'm trying to work out the basics: what do I need for parts? Essentially, after I tear out the steam boiler and its parts, it seems like I need:

1. A new hot water boiler, probably direct vented and around 110k output btus (I've tried to do some heat loss calculations, but there are a lot of unknowns with this house - this seems like a worst-case size for the house and I do plan to add a lot of attic insulation this summer)
   
2. Expansion tank sized to the new boiler (not sure how to size this)
   
3. Two circulating pumps (the house is piped with two 'zones', one the east side and the other the west side)
   
4. A relay for the pumps
   
5. Smaller diameter black piping and adapters to connect everything to those big herkin flanges at the end of the original large piping
   
6. Vent piping for the new boiler
   
7. New valves for the radiators with stuck valves (pretty much all of them)
   

Am I missing anything? Can anyone offer me any support/suggestions/encouragement? Any ideas about what boiler would be best/easiest for my situation? Good parts suppliers who can help DIYers like myself?

JakeCK

So you are going to convert from steam to hot water? That is quite an undertaking for someone who has no experience with this kind of work and is struggling to even figure out the heat loss.

Edit: n/m, just now read it. **** is that thing ?  Yea those rads are for hot water not steam. 

gchrisman

No, this was a gravity hot water system, which an incompetent contractor installed a steam boiler on. I'm going to be removing that and installing something that will be more appropriate.

Jamie Hall

Since it was gravity hot water before it isn't really all that bad. The gotchas -- which you may already be aware of -- come in balancing the flow to the various radiators to get the heat you want from them. That can be handled by your new radiator valves, although if there are distinct "upstairs" and "downstairs" pipes in each zone, you might add balancing valves on them.

Individual thoughts -- Item 1; double check your size, if you can. You don't want it too small -- but you don't want it too large, either. I would go with a pretty simple boiler. Fancy mod/cons are wonderful gadgets, but are tricky to get set up right -- even for the folks who do it all the time.

Item 2. I believe Amtrol has a tank sizing facility. The size they recommend will be too small, since you have the big pipes, so go up at least one size. There are accessories which usually sort of go along with the tank. Air removal gadget, and pressure reducing valve.

Item 3. You could use two pumps. You could also use one pump and zone valves.

Item 4. If you were to use one pump, the end switches on the zone valves could be used both to energize the pump and ask the boiler to turn on. You'll need an aquastat on the boiler to manage its temperature. Otherwise, yes you will need a relay -- Taco, among others, makes a nice line of controllers.

Item 5. Unless you are really happy threading pipe, how are you at soldering copper? Usually easier to do. And quite satisfactory.

Item 6. That depends on the boiler. The install manual will have pretty complete directions, but that is an aspect which your building inspector or fire marshal should also be contacted.

Item 7. Yup. Make sure they match, though.

On the whole, I'd say to go for it. It's not a one day job, and you will hit things which you have trouble with. When you do, get back on The Wall and we'll see what we can do.

jhewings

On the other thread Steamhead pointed out your boiler can work for hot water. It will still be a lot of work to re-pipe and change the controls but maybe you don't need to replace the boiler.

gchrisman

I looked at converting the boiler, but the manufacturer won't sell me the parts, and it would still be way too large for the needs of the house (by everyone's estimate).

hot_rod

A large volume system like that could be ideal for a mod con
Start with a load calculation
Consider any past or future building upgrades to get the load as low as possible
A radiator assessment to see what they are capable of at lower water temperatures.

Download Idronics 25 for some formulas and ideas.

Jamie Hall

The only reason I'm a little wary of a mod/con -- which as @hot_rod said would otherwise be ideal -- is getting it set up properly.

hot_rod

Jamie Hall said:

The only reason I'm a little wary of a mod/con -- which as @hot_rod said would otherwise be ideal -- is getting it set up properly.

Correct, you must have someone with the  tool and knowledge to setup the burner. An accurate combustion analyzer with the ability to use it
In some rare cases the burner needs to be set outside the specs in the manual. Knowing when and how to tweak optimum even reliable performance is best left to the trained pro.

piping, running stat wire can be done successfully by a technically handy person. 

109A_5

@gchrisman, If I was in your situation (I read your older post, what a blunder);

Plan 'A'. DIY a new boiler install (if funding and Boiler availability is not an issue) a correctly sized boiler for the home with all the appropriate recommendations above. Find a boiler you like and down load the manual and read it ahead of time. Learn all you can about these systems, many resources out there, be the expert (at least with what is in your home). Some issues or questions may be worked out before you even get the new boiler.

I would have a plan 'B' (which is not another cold winter in your home) in case of funding issues or the boiler you want is currently not available.

Plan 'B'. That existing boiler should certainly keep that house warm and comfortable. However probably not quite as efficiently as a properly sized unit. Download the installation manual for the 'like' hot water boiler, strip off the Steam boiler trim and build it out as a hot water two zone system, since it looks like there is a natural split (unless that makes no sense with the house layout or you are not interested). That work if done correctly the first time could be reused if the boiler is later replaced.

Things to do over the summer with either plan. Verify good flow through both pipes of each radiator and proper valve operation (harder to repair when the system is in operation). Air bleed valves all work correctly. Insulate the pipes unless you want the heat in the basement.

A high tech Boiler ? Your choice, My opinion, for me, no way. I like low maintenance costs and higher reliability, and yes I understand I am paying for that with less efficiency. I'd rather have heat when I need it.

I'm glad that carpet ? is gone that was in the picture in front of the older boiler. It looked liked like a fire hazard !!!

EBEBRATT-Ed

@gchrisman Did you try "find acontractor" on this site?? Where are you located? Someone may have a recommendation.

retiredguy

I am not going to add my ideas to this thread since you guys seem to have the problems "well in hand". So, correct me if I am wrong; converting a steam boiler to hot water is not that hard. You remove the steam trim and add aquastats and a few necessary controls. As for the gravity system, why not just repipe the piping at the boiler for hot water and add a very small circulating pump. It can't be that hard. Am I missing something?

gchrisman

Thanks, everyone, for the good advice and ideas. I think my first project is to complete a heat loss calculation, with whatever measurements I need to take - it seems that is the most important thing at this stage. From there, I'll investigate my boiler options. Because of my inexperience, I probably will stick to the simpler boilers, but I'll read some manuals to make sure I know what the options are. In the meantime, I'll replace valves and make sure the old pipes are open. I'll keep this thread updated, and will definitely ask more questions as they come up!

PC7060

EBEBRATT-Ed said:

@gchrisman Where are you located? 

Location would be helpful. 

pedmec

Sorry to hear about your boiler. But i have to say i'm shocked. I cant believe what i'm seeing. I truly believe that the installer is not a heating contractor, most likely a handyman. i don't believe there is any legitimate plumber/hvac contractor that wouldn't know the difference. the funny part is he didn't even pipe the steam boiler correctly either. lol.

Good thing for you is you can convert that steam boiler to a forced hot water boiler fairly easy. So the boiler doesn't have to get trashed. But please get references next time. don't attempt this yourself. It should be fairly cut and dry for a reputable contractor to fix correctly.

gchrisman

For location, I am in a tiny town in south-central Iowa, with very few good contractors around. I have had similar trouble getting help with plumbing (or anything else for that matter). I moved here recently to fix this house up, and have been shocked at how difficult it is to get any real professional help. The ones in larger cities are busy in their own area and don't want to travel out into the country (especially for difficult and complicated projects, it seems). So, I've been learning a lot about doing various things myself...

I took a lot of measurements over the last few days and crunched the numbers for the heat loss calculation, making a few assumptions about the R-value of the walls and foundation. The house was built in 1908 and has had very few updates. The house has a full basement with 24" thick limestone walls and concrete slab, unheated except for the large pipes of the gravity system. I ran the calculations taking into account the insulation I'll be adding to the attic later this summer, and the storm windows I'll be replacing as well. What I came up with was a required BTU output of 90,100 at the low end (assuming R-6 for the walls, which are thick wooden siding, dimensional lumber, newsprint 'insulation', and original limestone plaster & lath) or 100,300 at the high end (assuming R-4 for the same walls). This means that the existing boiler is hugely oversized, besides being set up for steam.

I've been looking online at some boiler options, but does anyone have any suggestions of particular models or brands given my needs?

hot_rod

You need to decide if a basic cast iron boiler is the best option, or a mod con. Both will have OEM electronics that can fail and put the system down. It may come down to availability regardless of thew type or brand.

I've done trainings at a distributor in Fargo and a handful of the plumbers were still converting new cast boilers to standing pilot for their remote installs That is about as simple and trouble-free as you can build a boiler. Probably not a factory authorized conversion however.

That same branch had 15 year old Munchkins heating their own building, last I was there.

109A_5

hot_rod said:

That same branch had 15 year old Munchkins heating their own building, last I was there.

I smell redundancy here.

I really like my thermocouple changes (can't remember the last time, I have spares, and inexpensive) and the fact I can run my boiler from a battery. Maybe a dying art (or technology) but it keeps me warm during a power failure, and I probably don't miss the many $100 or $1000 repair bills. I do consider my self lucky to have old school steam heat. If I had Hot-Water heat I probably would have a Plan 'B' low DC Voltage circulation pump.

I seem to read a lot more about expensive high tech disasters on this site than 'how do I change my thermocouple'. Some folks get lucky and change a sensor themselves. To each His/ Her own I guess.

109A_5

gchrisman said:

I've been looking online at some boiler options, but does anyone have any suggestions of particular models or brands given my needs?

With the present supply chain issues you may want to see what is actually available in the BTU size you desire, then make a choice of actual available units.

gchrisman

I'm working on choosing a boiler - and probably overthinking everything. Soon I'll just have to pick one and deal with it from there. In the meantime I've been replacing radiator valves, removing two badly-added radiators, and redoing a few pipes. I do have a question: is there any reason I can't use 1" oxygen barrier PEX intended for radiant heating as near-boiler piping when I redo that? It would be much easier than steel or copper. The max temp on it says 200 degrees, and I'm planning to run mine at 170 or so.

mattmia2

You would want to use copper or black iron until you are some distance away from the boiler to protect it from the heat from the boiler and the vent, after that it can be pex. Pex will require more support.

gchrisman

OK, the comment about making sure of what was available was spot-on. Not a lot of stock in my area right now. So, I am thinking of going with a Rinnai I-Series i120SN, which can be set up for LP without needing a flue gas analyzer, has a premade primary-secondary piping kit I can buy to simplify that part of the install, and built-in controls for up to two pumps (though I'm currently leaning towards only doing one Bell & Gossett Series 100 pump since I don't really need the 'zones' operating independently). The direct-vent will be much easier with 2" PVC, the boiler manual mostly makes sense to me, and the boiler itself is much smaller and easier to deal with than the heavy floor units. Any input?

I'm also trying to work out the expansion tank - most of what I'm reading suggests a compression tank for a gravity conversion like this, but is there an easier or better way? How do the two types of expansion tanks interact with the air eliminator? I like the idea of bleeding the air off automatically, or at least more easily.

EdTheHeaterMan

I have installed one of those. It is easy enough. I'd go for it.

WOW... I read the original post about the steam boiler replacing a gravity Hot Water Boiler... What a Maroon!

I think you can handle it. The B&G 100 is probably overkill. You may find that a Taco 007F will be more circulator than you need.

Your near boiler piping can be 1" from the boiler supplied manifold thru your air separator and your circulator pump. You can tee to each supply in 1" copper. AS LONG AS THE LOAD CALCULATION IS LESS THAN 80,000 BTU. otherwise up the copper to 1-1/4". Then you can tee to each return in 1" copper. Then you need to get some bushings from each of those flanges that will get you to a 1" PEX adaptor. Then use a PEX adaptor to each of those copper tee fittings. Make the PEX start about 5 ft away from the boiler. You might place the boiler further away from the existing supply and return flanges from the radiators just to make sure you are far enough away.

This is the picture i would give my son as he goes forth and installs that boiler.


I added some balancing valves to the return. This may make it easier to get those 2 sections closer to working properly without adjusting all the radiator valves individually. By adding one more valve to the common supply pipe, you can isolate the large volume system so you do not need to drain the entire system for a near boiler piping or component repair. Just a thought

Mr.Ed

EdTheHeaterMan

If your load calculation is more than 80,000 BTU then I would use 1-1/4" copper piping and such to connect the near boiler piping to the factory supplied manifold. From the 1-1/4 copper I would split to 1" using a 1-1/4 x 1 x 1" tee (on both the supply and the return). And as you mentioned, all PEX must be O2 barrier PEX.

gchrisman

Thanks so much for those diagrams, Ed! They will be a big help. I'll go with the 1 1/4" piping, since the load calc is 90k BTUs or so. One question - the primary/secondary piping I found for this specific boiler doesn't have the mount for a boiler pump, but the manual for the boiler does show a boiler pump close to the boiler as in the diagram you posted. Do I need both a boiler pump close in and a system pump on the supply pipe, or can I get away with one pump? If I do need a close-in boiler pump, what sort of pump should it be? If I do go with the 007 Taco for the system pump, I was looking at the 3-speed one so I can fiddle with it to get the flow right.

mattmia2

I would go with Lochinvar or HTP based on what I have seen here but whatever it is someone will need to do a combustion analysis on it.

I wouldn't worry a lot about the system flow as long as you have a boiler pump that can keep the minimum flow through the boiler. Note that a water tube boiler will have a lot more resistance than a fire tube boiler.

JakeCK

I just want to add that you really should consider Ed's suggestion about isolation valves. 

Take it from someone who has a system that has basically no valves that it is a royal PITA to do any kind of work on the boiler. And everytime it means I need to drain down and then add all new fresh oxygen loaded water to the system. 

gchrisman

I will definitely put in all the valves I can. I learned how valuable this is when I was doing my plumbing!

PC7060

Re the 2” vent, PVC may not be allowed depending on your local or state codes.  There are several approved alternatives including System 1738 pipe and fittings available from Fergusons and Ayers.

https://www.ayer.com/system-636/system-1738-flue-gas-venting.html

I’ve seen other options as well on the site; I recall a couple systems posted by @gw that used a modular system that didn’t require adhesive. 

gchrisman

Now your comments have me looking at the Rinnai versus the HTP boiler. The advantage to the fire tube boilers would be less of a pressure differential, correct? And that means I would have an easier time getting the system circulation to work properly? What is the overall difficulty I would have with a water tube boiler in this type of system? Just trying to understand and make the best choice for my situation...

gchrisman

I finally ordered a boiler and all the bits and pieces I'll need. Based on the crud I'm seeing in the pipes I've opened, I'll need to flush the system. Once I have the incorrect boiler removed, what is the easiest way to flush the system out? I'm picturing just temporarily connecting the water feed to the supply pipes with a manual valve, pipe the return pipes into the floor drain, and have at it. Hopefully this will also turn up any leaks I may have in the radiators and pipes as well. Is there a better way?

EdTheHeaterMan

gchrisman said:

I finally ordered a boiler and all the bits and pieces I'll need. Based on the crud I'm seeing in the pipes I've opened, I'll need to flush the system. Once I have the incorrect boiler removed, what is the easiest way to flush the system out? I'm picturing just temporarily connecting the water feed to the supply pipes with a manual valve, pipe the return pipes into the floor drain, and have at it. Hopefully this will also turn up any leaks I may have in the radiators and pipes as well. Is there a better way?

That sounds right but you may not get all the gunk out that way.

You may want to purchase one of those Dirt-Mag devices and place it on the return piping just before the boiler inlet. properly places valves can help you with the flushing clearing and cleaning of the old system. Here it is in the diagram with 2 more valves and a boiler drain for flushing.

The red valves will isolate the new work from the old dirty system. Close both valves. Now by opening the fill valve to the system at full house water pressure, you can force water thru the system one zone or one section at a time. Then do the other zone of section by closing the open isolation valve and opening the closed valve to flush that side. Let the water run for as long as you want. 20 minutes should be overkill.

The orange valves are the isolation valves that double as balancing valves, from the previous illustration. The 1-1/4" Red valves are both closed (indicated by the yellow handle) The light blue dashed line indicated the path of the house water pressure flushing the old system, until it exits at the boiler drain with a green hose attached.

You will not get all the sludge from the bottom or every radiator (unless you close all the radiators and flush only one at a time for 3 minutes or so then close that radiator and move to the next.) but the Dirt Mag in the location indicated will keep the gunk from messing up your new boiler. After the system is up and running, operate the boiler and check the strainer and magnet the next day, depending on what you pick up, you can determine if you can wait longer, like a week, or a month. Eventually you will only need to check it annually as long as you keep your water chemistry just right.
https://www.supplyhouse.com/Caleffi-546335AM-1-1-4-Sweat-5463M-Series-DIRTMAG-PRO-Dirt-Separator-w-Dual-Magnets

JUGHNE

Ed, one suggestion for your piping diagram; the LWCO is up on a riser and could possibly have an air pocket below it. This would make the probe in a dry well.

If it had to be there I would tee in a small auto air vent....another potential leaker though.

I believe it would be better in a vertical riser location that is still above the boiler water level.
But IIWM, I would still locate it below an isolation valve in order to remove the probe for cleaning without draining the entire system.

IMO, any component or device that is screwed into the boiler/fittings/piping etc should be able to be isolated from the radiation piping. Then you have to bleed air from the boiler and close piping only.

This lesson was learned by having a new relief valve dripping that picked up a copper shaving in it's seat.
This was a 3 story house with many radiators and required purging and air bleeding for all of them.

So when boiler replacement happened there were multiple isolation valves installed.

gchrisman

Thanks for the help - I already have the exact DirtMag you suggested! I'll get it piped as you drew it out, with lots of valves. Question - if there are leaks anywhere (in the CI radiators or piping), they should be revealed by this flushing process, right? In other words, if I don't get leaks during this, it shouldn't leak when I'm using the boiler for heat, right?

Thanks for the hints on the LWCO, too.

mattmia2

The flushing won't put much pressure on it. You will see big leaks but you might not see small leaks until you fill and pressurize the system and even then if it is evaporating faster than it is leaking you might only see some crusty residue.

gchrisman

I'm just dreading getting the new boiler set up and working, only to find multiple leaking radiators. From what I've been reading, if they have serious leaks they really need to be replaced.

mattmia2

Why do you think you'll have leaking radiators? It happens occasionally, but more than one and suddenly usually only happens if they freeze with water in them

gchrisman

A couple of the radiators have visible corrosion at the joins between the segments along the bottom, and the floor under others has stains that could be from past leaks. The house also had plumbing that had frozen in the past and split the cast iron stack pipe (I had to have it lined with plastic). Plus, I'm just at the stage on this house project where I expect the worst...

mattmia2

Then it might be worth it to cap the existing piping, hook a hose with a gauge and a valve up to it and fill it up to 25 or 30 psig or so and leave it for a few days and see if it keeps pressure.

hot_rod

gchrisman said:

A couple of the radiators have visible corrosion at the joins between the segments along the bottom, and the floor under others has stains that could be from past leaks. The house also had plumbing that had frozen in the past and split the cast iron stack pipe (I had to have it lined with plastic). Plus, I'm just at the stage on this house project where I expect the worst...

I think the deck is stacked against you if the home went through a freezing condition.

gchrisman

I'm making some progress - I removed the incorrect steam boiler, and have started in on the setup for the new one. The steam boiler is absolutely filled with crud from the old pipes and radiators, which explains why it was less and less effective as last winter wore on.





Once I got everything out of the way, I connected the water feed directly to the radiator supply lines, and ran water through the system for a while. The good news is that the water was running pretty clear at full pressure. I turned up two leaks in this process - one union in the basement was just gushing, and the union on one of the radiator valves on the ground floor just dripped. Both are hopefully patched up now. The new boiler (an HTP mod-con unit) should be arriving today, and I'll get started on piping the whole setup as people have so nicely diagrammed above.

There is an extra electrical box that seems to be a relay of some sort - I don't know yet whether I'll need it as part of the new system or not. Probably not...

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