Excited about Boiler Design
On one side of the house, we have a porch with crawl space and the basement chimney goes right through it. That’s where the largest basement room is currently and the Weil McLain CGa 7 Gold and two water heaters utilize one half of the fireplace chimney. It’s a good spot for a hot boiler. However, most of our water use is on the other side of the house that also has the floor drain. So any leaks in this semi-finished area of the basement with the boiler and water heaters just runs across the whole darned floor. I want to install a modcon on the other side of the house, maybe a combi, and maybe a storage/buffer tank and maybe a hot water storage tank and/or heat pump water heater for summer hot water. Part of this move is to also free up the chimney to be able to burn wood. Hearth.com also got me excited about maybe even adding a wood boiler there. I’d like to put a pool/ping-pong table over in that area of the basement too. Maybe just a wood stove makes more sense.
So I am thinking that, at least for the short term, I want to make a large primary loop for the boiler so I don’t have to re-pipe every radiator and all the zones. That honestly might make sense in the end, but makes the project monumental. So I am thinking I can add the modcon boiler on the other side of the house, add the big loop, and just swap the connections with the existing boiler. I would think that doing this all in PEX would be economical, and also make it very easy for me to alter in the future. I don’t think I want microzones, but perhaps a buffer tank would enable that if desired.
I see some say primary loops should not be done with PEX, at least not close to the boiler. Does anyone have a strong opinion on this? Also, I am only familiar with smaller PEX sizes, and honestly I’ve never seen or worked with anything larger than 3/4”, having tools for 1/2” and 3/4” for potable water. So working with PEX in 1” and up will be new to me.
I am in love with Triangle Tube products and am now debating over Instinct Combi 155 and 199 which seem just so darned cheap it’s scary. One reason I like the Combi idea is because I want to buy an identical unit for my 2 story garage / pool house project. That would mean I’d have parts ready to steal from the garage in the event of a failure. The garage isn’t somewhere I really want to have a tank, and it’s only got a cold water line out to it now. Hot water line from the house just ain’t gonna happen, but I do have a spare 2” electrical conduit from the house to the garage. So it’s not impossible, just not likely.
I would be interested in hearing the opinions of others and wonder if I should put together some diagrams or photos and videos to help get advice from others.
I am really excited about building my Raj mahal of hydronics.
Another thing I am curious about is if we should try to staple floor heating under about 1.5” of wood flooring from the basement. Currently we have cast iron baseboard heaters (not original to the 105 year old house) on 90% of the first floor that is on its own zone. With all the cast iron plus the boiler in the basement, it gets to 76-80 F down there, which I’m sure is a real waste of energy. Putting my winter office down there might save some heating though.
Anyway, I’m looking to design my dream system for my dream house. Thank you in advance for any help I receive here.
Some older exterior pictures are below to get a sense of what I am working with.
Comments
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anybody here work with wood fired boilers? I think that would be cool to have a second boiler added to the primary loop to be able to heat with wood. Unfortunately, I doubt that any of them are as pretty as a wood stove. https://www.hearth.com/talk/forums/the-boiler-room-wood-boilers-and-furnaces.13/
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Well… the project is certainly feasible. The biggest problem with PEX — any size — is that when it's handling hot water (even domestic hot water) it pretty well has to be in a trough or hung at very close intervals to avoid sagging. It is rated for use up to 200, but the manufacturers aren't really happy over 180, but that's high enough for your use case.
Insulate the dickens out of it. You don't want the heat just wandering around!
Size it for the BTUh load; even one inch may not be big enough.
I at least would be very cautious about an indoor wood boiler, unless you have a captive firewood supply like your own woodlot — and the time and energy to make you own wood. You can do some figuring on costs, though: most eastern hardwoods run around 24,000,000 BTU per cord, so you can do some math and compare the cost per BTU to whatever you are using now. A cord of wood is more or less equivalent to 150 gallons of fuel oil.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
Wow. A cord o wood equal to a gallon of fuel oil. We have natural gas here, something I may have neglected to mention. I guess a wood stove for ambiance and extra heat probably makes a on more sense than messing with an indoor wood boiler. I have yet to find any pretty ones. Maybe for the garage near the swimming pool it could make sense to be able to heat the pool with biomass instead of natural gas. So I will maybe keep researching that a bit.
For the piping size, I think my existing 210k btu in, 175k BTU out Weil McLain CGa 7 has 1.5” pipe. I guess I could just use whatever is on the boiler I buy though. It looks like each of these combi boilers have 1”. So maybe that’s all I will need. Perhaps there would be less heat loss with larger pipe though. I didn’t know.
https://triangletube.com/products/gas-condensing-combi-boilers/instinct-wall/I can put the pipe on top of 2x4 to support them around the basement, maybe up in the joists. So I don’t anticipate that being a major concern.
As for temperature, I never ran anything over 155 F in my old house. I assume this house will be the same, but if I was to run an indirect water heater, I guess that loop would get hotter probably. That would be next to the new boiler in the existing laundry room though.So this is all sounding doable.
I am curious is those TT Instinct Combi models will have the ability to have an indirect tank attached with a higher firing temperature for DHW. I’m not expecting them to have this, which is the only thing holding me back from purchasing one of those Combi models. Also deciding between 155k and 199k and being concerned that they are made with inferior quality parts. I was very happy with 14 years of TT Presige Solo ownership but always used a standard gas water heater. This will be my first time ever trying anything else, and I am looking at all the following:- tankless in a combi
- Indirect fired
- Heat pump for summer hot water
- A hot water storage tank to assure we don’t run out or have flow rate issues. Not exactly sure how to do this yet.
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My opinion as an installer, if you want the best long term system, don't do a combi. Yes, they work and I put them in, especially for small houses or apartments, but I consider an indirect a superior option.
My opinion as a long time heating-with-wood person is, don't do a wood boiler. If you want to burn wood get a good looking woodstove and fire it up on that bitter cold weekend that you are planning to spend at home. Nothing beats a cheery fire while the snow flies outside. (Well yes, love at home beats it but why not have both!)
As for triangle tube instincts, they are fine. However, they do not have near as many setting options as most manufacturers and do not modulate as low, but the argument could be for their simplicity. They do not have settings such as differential, time on minimum fire and time to max fire. Those settings can greatly mitigate short cycling even without a buffer tank.
And yes for a HPWH if you have the proper criteria to take advantage of its features. They do great for summer HW in an unfinished basement where they also help with humidity.
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so if an indirect is superior, and I don’t want a tank in the garage. Then the concept of buying an identical unit goes out the window. It might be cheaper to just buy the “most-likely-to-fail” parts like a did for $500 a few years ago for the TT Presige Solo 110 at the old house.
On the old stove, I actually already got two VC Encore units, one for the garage and one for the basement, but have less than $300 into the pair at this point, so I can pivot. The garage boiler really is not needed any time soon, especially if the wood stove is up and running. I am thinking that o should buy the replacement boiler for the house this year, but I guess my improvements today might help me get through the winter.
today I added the Taco SR503-EXP to my boiler to be able to run wireless Internet thermostats and also have the boiler shut off when no zones call for heat. That might help my system run a bit more efficiently and at least enable me to up the boiler temp now if I want (without getting all the popping and banging due to the lack of a primary loop and t-stat shut off
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Travel over to the ISH show in Frankfurt this March. They have an entire hall dedicated to solid fuel burning stoves and boilers. Cordwood, pellet, chip, biomass fuels.
Parlor boilers are designed for the ambiance and a small hydronic load. Hundreds of them from countries around the world on display. It is a hot Hall as many of these units are actually running.
Some examples from Austrian manufacturers
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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Why is it that we here in the US can't seem to make or decide not to make an attractive wood stove? They all seem to look like a television from the 80s or an attempt at redesigning the Franklin stove. If one likes that look that's fine but the real attractive options (to my eyes at least) are all coming from eastern and northern Europe.
Those are beautiful @hot_rod
Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker1 -
I hear the logic on not buying a combi, but I think my garage / pool house project will be a place where I don’t want a tank of water I need to keep warm (from freezing). So I think I have decided to buy ONE TT Instinct 199 Combi to put in the house, and if it doesn’t work out, I can move it to the garage and do something else. Meanwhile, I have told my family what I want for Christmas and sent the link.
My next step will be acquiring parts I am going to need for the install.- primary loop piping to get to the old boiler location
- expansion tank,
- Condensate drain setup, etc
- Organize laundry room and reconfigure the washer dryer, etc.
I’ve got a lot of junk to eliminate, and perhaps my highest priority for this project will be setting up an office in the basement for this winter where I can sit toasty next to the boiler (saving even more money keeping the house cool). There are also drafts down there I need to address. It will be a great project space, and I think my wife will appreciate me cleaning up my first floor office.
I will report back here when I am ready to design tank storage for the hot water and digest stuff like this link.
I think I will also start trying to educate myself on heat pump boilers to have setup in the basement for next summer. Also, finding the ideal location for a heat pump water heater in the basement will be on my list. Do I put it close to electric and fixtures, and maybe add fans to circulate basement air? Or do I just put it close to the main room that I hope to finish and make livable space? The warmest area of the basement would clearly be the best place to extract heat. It almost makes it sound like putting it on a higher floor in the house could be a wise move (aside from the potential for leaks and complexity of altering plumbing). I don’t know. But I will learn.
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Nicest wood stove I had to play with was a Jotul 601. Simple. Straightforward. Worked like a charm. heating about 800 square feet of space in Vermont in the winter…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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So I see boilers are selling out, and I was about to click “buy now” on the 199k BTU input combi, but figured I should look at whether the minimum firing rate would be too high. Oversizing it would be bad.
We do use natural gas for the cooktop and recently added an outdoor grill, but I think that the grill is negligible during the winter months, as I encourage indoor cooking when the heat is on and outdoor cooking when the AC is on.
I took our CCF / mo for the past 12 months and then saw that 6 months November to April are when all the fuel gets used for the most part, 1244 CCF vs 186 CCF anyway. So if I want a boiler to run at its minimum firing rate for 6 months straight to provide hot water and heat, I’d want to break down the 1244 CCF into the hours. I come up with 29.5k BTU INPUT consumed per hour. We have an 83% efficient boiler and probably 60% efficient water heaters: if I just use 80% as a guess at our efficiency, then the OUTPUT that the house consumed was actually 23.58k BTU/hr.
I see that the 199k BTU Combi would likely be a bit oversized with a minimum input of 25k BTU and 95% would be 23.75 k BTU.I do hope to make the house far more efficient in the future. So there’s consumption should really drop, especially as kids move out. So that could be another reason to reduce the size.
So there’s a balance between quick recovery and endless hot water (all provided by the boiler) and efficiency:
I have setup a desk in the basement next to the existing boiler and two water heaters. 210k BTU on the boiler, and 40k BTU on each of the two water heaters. I primarily have the second setup as a storage tank though. So even though we have 290k INPUT BTU of heating power in this basement, it’s only fair to call it 250k BTU.I think we could get by with the smaller 155k BTU input combi, but I think I am going to be safer with the 199k BTU one, and if it fired for 6 months straight at its lowest firing rate, it might actually be perfect. I just don’t know where we’d be able to store all that heat to make it through the coldest moth.
So I looked at the coldest month, ending Feb 12. 306 CCF /31 days = 42.7k BTU/hr.
If I was able to store heat, it looks like ~43k BTU/hr input would have gotten us by, like a 55k BTU/hr combi boiler at 80% efficiency running at 100% firing rate all month would have been ideal I guess. The problem with that sizing is that it least zero room for ramping of the heat.
Last year I kept the house very cool when possible to minimize heat loss. I know ramping up could consume more, but I am certainly doing more of that this year. We also kept the heat in the den essentially off and closed off the room. I am about to insulate so we can hopefully use it this year. I don’t know how that balance will play out.
I think I’m going to buy that 199k BTU boiler before it’s gone. Wish me luck.0 -
I clicked the “buy” on the 199k BTU Combi. I will plan on also adding a storage tank after the Combi for DHW. I think that the most ideal setup will be to have a heat pump electric water heater to make cool in the basement that is used primarily in the summer. I’ve read that a regular electric water heater is just fine for this. So maybe I will consider that route also. If I went with regular electric, I could also set it at some minimum acceptable water temp for year-round use and also maybe save a few bucks. So this will be something to think through. I have two gas water heaters that could also be used for nothing more than tanks too (since I believe I will want to move them far from the chimney, making room for the wood stove.
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I looked at my hourly usage over the last year nd discovered there’s only about 3 hours where we used more natural gas (cooktop, two 40k BTU hot water heaters, and the 210k BTU boiler) and I discovered there’s only were only about 3-5 hours during the entire last year when we used more than 1.5 CCF. So I initiated a cancellation with the seller and will see if I can get my hands on TWO 155k BTU combi units, one for the house (with a DHW storage tank/electric/heat pump water heater, and one for the garage as straight up tankless DHW where I may look to also use pool water as a heat sink maybe with a tank in the garage for that. Not sure if that’s a terrible idea with the pool chemicals, but that heat exchanger would need to be deigned right. The problem with the garage is not having enough heat emitters. So that could be interesting. But I do want to get two identical units. I totally forgot about that when I clicked Buy hastily this morning when I saw only one boiler remained. No rush here (I don’t think anyway).
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OK. Buyers remorse situation resolved. They refunded me, and I placed the order for TWO Instinct 155k BTU Combi boilers, one for the garage, and one or the house where it should be the most efficient option, feeding into a Heat Pump water heater as a winter storage tank, and summer hot water producer. It could also be used to help balance the load. If the Combi has issues with hot water flow rate, I may need to figure out a way to have some amount of water bypass the Combi and go into the get pump water heater to make up the difference. But maybe it will be perfectly ideal to help assure the hot water usage is under control. I’ve got 3 teens in the house right now.
Anyway, figuring out what her pump wat hear to purchase will be coming up next.
The per topic will be a buffer tank for thermal mass storage to be able to handle microzones. How much do I need? And is an old natural gas’s hot water heater sufficient? I’ve got two of them I. My basement that I will be planning on eliminating. I can wrap them in insulation like nuts and keep them in the laundry room where there’s a floor drain in the event of disaster. I bet they will last much longer if they have the lower pressure heating water in them AND they are not subject to fire that they get every day. I can also be sure I design everything so it’s easy to remove a single component with valves that assure the ability to bypass o include optional components in my install. The buffer tank(s) would be one of these I the heating, and the heat pump water heater would be another in the DHW.
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Two Triangle Tube Instnct 155 Combi boilers “purchased” and will be waiting a while for hem to show up.
One will go in the garage where I aim to create a studio apartment above he garage with one full bathroom, and downstairs in the garage have a kitchen, plus n outdoor kitchen / grilling area. I don’t plan to have any storage tank for hot water, just rely solely on the combi for DHW. I will probably have four total radiators, cast iron ones I already own.The more important Combi will go I. The house where I believe it is sized right based on my hourly consumption over the last year, with only over 1.5 CCF / Therm getting used in ~3 hours over the course of the year. 1.7, 1.8 seemed to be the numbers, and that includes cooktop, 210k 83% efficient boiler, and two 40k BTU water heaters. If I implement a storage tank f the DHW, I think the 154c will cut the mustard. Plus, if I need parts, I can steal from the garage unit that will be identical.
Deciding on a heat pump water heater is next.
Also, deciding on buffer tank(s) and if I should use the two natural gas water heaters I’ve got, just because I have them… that’s also on the list. He price is right.That would only leave me with the cast iron Weil McLain CGa 7 Gold 210k in, 175k BTU out boiler in good shape to sell. I might be able to get a few hundred bucks for it. I don’t know. I might as well guess a shot at getting it up for sale, but maybe I better wait until I at least have the TT hub on the wall first.
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are you talking about trying to redesign systems unnecessarily? Or are you talking about trying to DIY design and install all the stuff?
on the first question. This is more of a renovation that I don’t expect to save me that much on a monthly basis. Rather I am making long term plans for the future with the renovations. I am creating usable living space in my basement and in my garage. The garage could possibly be rented out and make back all the money in short term. The basement is just something I want to do. Ripping out the High Velocity ductwork for the AC and redoing that will be ANOTHER project too. This is our dream home, what I call “a worthwhile project.”
On the DIY, I want to get what I want, not what someone wants to sell me. I am not opposed to hiring people to install what I buy, but I will likely make all the decisions because I had a terrible experience with the last pro I hired for a modcon inatall, teaching him everything he knew about modcon boilers by the end of it all.0 -
I feel it’s time to start researching heat pump water heaters. I should not NEED one for the house, but I want to know what is available on the market. So here are a few I have found.
AO-Smith:
https://www.supplyhouse.com/AO-Smith-HPTU-50N-50-Gallon-Voltex-Residential-Hybrid-Electric-Heat-Pump-Water-Heater
Stiebel Eltron (very expensive):https://www.zoro.com/stiebel-eltron-water-heater-heat-pump-80-gal-233059/
Rheem:
NY Times likes he Rheem it seems.
Edit: TWO THINGS are making me second guess this whole heat pump water heater thing.- Not a wide variety of products / vendors I am finding and high prices. Yeah, $1700-2500 isn’t terrible, but bc I only plan to use this as a storage tank and summer water heater, this feels high especially compared to the cost of the combi.
- One of the 120 Volt versions I saw had a map showing that it’s not a good product for my area, only good for the south. Using electricity to steal heat made by the heater is two steps to get the water hot and can’t be too efficient. I. The summer time when you are trying to get rid of heat, I understand it must be more efficient.
Anyway, I am starting to think I can postpone the heat pump water heater portion of this project a couple years down the line and probably just use one of my two existing water heaters as a DHW storage tank or maybe pickup a cheap electric water heater. I wonder if I need a special tank with an aquastat shown here: https://www.bradleycorp.com/sizing-tankless-water-heaters/on-demand-water-heater-with-hot-water-storage-tank
I wonder if the other water heater can be used for heating water storage. I will have to see if I can find a diagram to follow for thermal mass storage.
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some useful info regarding HPWH,s
https://idronics.caleffi.com/sites/default/files/magazine/file/idronics_33_na.pdfBob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
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