LONG Introduction of my DIY project and some questions on boiler, controls, etc.

EPMountainMan

Greetings, All. I am brand-new to this forum, but have been lurking quite a while, just soaking-up all of the wonderful ideas and information offered here. I am in the process of re-building my own home from the inside-out (long story), a 2,600 sf rambling mostly-ranch-style "cabin" that was added-onto 11 times from 1917 to 1989 up in the mountains on the Front Range of Colorado (7,500 msl, town of Estes Park).

Personally, I am an architect and DIY homebuilder, through the last 20 years this being home #5 that I have remodeled/ rebuilt and hopefully my last. I do all of the trades myself and will occasionally sub-out parts of the project as the building permit will allow.

I bought "Siggy's" Modern Hydronic Heat book as well as his wonderful software Hydronics Design Studio to help me in the designing and building of a modern hydronics system on this home. I am also making my way through Caleffi's awesome Idronics series.

As-built with modern polyiso insulation in walls and ceiling, my heat loss on a design day (-7F) is 49k BTU. I also have estimated ~50k for worst-day DHW and up to ~50k if we choose to heat our spa from the same source. I am going with a sandwich-style radiant floor heat, 1/2" PEX-AL-PEX with omega-style plates, and some radiant walls in bathrooms and the entry and hall spaces where my flux in the floor can't quite handle the loss from the windows/doors. I also have a conditioned crawl space that I need to decide how to heat enough to keep pipes from freezing (fan coil or traditional baseboard, maybe?). Also on the wish list are towel warmers in the bathrooms. Floors are 1/2" strand bamboo in the living areas and porcelain tile on backer board in the entry areas and bathrooms.

Consequently, I think I am looking at a multi-temp system to cover the living/bedroom floor heat (warm), bath heat (somewhat warmer) and towel warmer and crawl space heat (even warmer, if not HOT). I am intrigued by injection-mixing and/or Siggy's "minitube" method and I am still in the process of selecting and vetting a heating pro for boiler selection and install. One of my dearest friends is a general HVAC guy that carries the Hybritherm boiler system (http://www.hybritherm.com/wp-content/uploads/2017/01/Hybritherm-Worldwide-specs-sheet-20171.pdf) which looks to me like a multi-temp mod/con. I haven't found any reference to their make/models here on HH, and would love an opinion on Hybritherm vs. WM, HTP, Lochinvar, etc. I would like to eventually add some DIY solar heat and a huge buffer tank in the crawl space to supplement the boiler, if the wife will tolerate another project.

I happen to own a spare WM CGa-5 cast-iron traditional boiler that I found used for $50 (!!), but its 117k DOE rating coupled with my heat loss and predominantly low-temp system seems like the wrong choice with much of my natural gas bill going straight up its 6" flue while it waits to fire again and I fight flue gas condensation with buffering, controls and resets. Whatever the final choice, I know that I want outdoor reset and some availability for turn-down in parts of the house because we are soon to be empty-nesters with a 5 BR/ 3 BA rambling home (I have insulated the common walls to facilitate a guest wing that turns down when unoccupied).

OK, so that's a LOT to digest, so thanks for bearing with me. I would sincerely appreciate any advice/recommendations to aid me in selecting the boiler, controls, pump(s), etc. I am currently installing the sandwich tubing and floors and will be ready for the common piping and manifolds next.

Warm regards,
Brian Brown
Estes Park, CO USA

HVACNUT

I personally think you shouldn't wing it by yourself. Stopped reading after a while cause you've got too much going on there. Open your wallet now, or open it wider later and bring in a reputable heating contractor to go over all your options. He'll probably have recommendations you haven't even thought of. Unbelievable right?
I'd say let 'er rip and have fun but I think (and your wife probably thinks) your biting off more than you can chew and sooner or later somebody has to give you the Heimlich.

Jamie Hall

Intriguing unit. I have two concerns about it, however. First is that it appears that it modulates between 100 and 27 btuh for the smaller natural gas unit, and 110 and 34 for the LP version. Those values may be significantly less at your elevation, by the way. In either case, though, it is really too big -- by a factor of 2 -- for your application -- unless your spa and building will require heat at the same time all the time. The second concern revolves around parts and service. Your friend carries and services it -- but just how generally available is service? And how available are service parts? It's not a simple device -- and Murphy is alive and well, and usually visits on the coldest day of the year.

HVACNUT

> @Jamie Hall said:
> Intriguing unit. I have two concerns about it, however. First is that it appears that it modulates between 100 and 27 btuh for the smaller natural gas unit, and 110 and 34 for the LP version. Those values may be significantly less at your elevation, by the way. In either case, though, it is really too big -- by a factor of 2 -- for your application -- unless your spa and building will require heat at the same time all the time. The second concern revolves around parts and service. Your friend carries and services it -- but just how generally available is service? And how available are service parts? It's not a simple device -- and Murphy is alive and well, and usually visits on the coldest day of the year.

Excellent point! I wonder why they don't show what it looks like with the cover off. 3 internal circuits, 1/2" pex connections. I don't know. I like all my branch circuits where I can easily access and repair/replace them. I'd love to see inside. Pandora's box?

Zman

I would recommend a fire tube mod/con with a track record at altitude. Triangle Tube had that market cornered for a while. I recently did a Lochinvar WH-85 and really liked it. I would not consider an off brand boiler for your application.

There really is no reason to do multi temp. The DHW could be a priority. Everything else could be designed for the heat loss of the space at allow low return temps.

Solid_Fuel_Man

I agree with Zman. With the correct tube spacing to match the calculated loads in different areas you should be able to have all heating to operate on the same temp. This not only simplifies things, it also makes a mod/con more efficient and saves you money forever, just like that polyiso.

If you have the software and are in it to do it right the first time, there is no reason you can't do it all yourself. Before I had lots of licences and certifications I was an avid DIY and made things work with a tendency to overbuild/overthink.

As you may already know, your homework now will pay big dividends later.

EPMountainMan

Many thanks for the ideas and advice. I have calls into some regional pros and will hopefully get one of them on-board soon to assist with the final build-out.

My only reason for wanting different temps in the bathrooms was for a wet and barefoot-friendly floor, but it's probably not worth the complication of mixing and delivering temps a few degrees warmer there. It was also my understanding that a towel warmer needs some fairly hot water to be effective.

My loops and zones average water temps are all within about 7 degrees of each other and am targeting 115F supply temps with a 10 delta T. Siggy's panel design procedure is fairly straightforward except for the k value, which I believe does not address tube spacing and floor covering with enough precision. Small changes to that number in my spreadsheet can make a huge difference in req'd. water temps. Likewise, tubes near exterior walls that are spaced a little tighter can't be calculated simply. Of course, there is nothing simple about the ASHRAE design graph addressed on Bean's site... http://www.healthyheating.com/How-to-use-the-ASHRAE-design-graph-for-radiant-panels.htm#.WLGql_krKhc

Any ideas on that procedure of the design or am I over-thinking it?

Gordy

One has to remember that in the bath you are planning for a towel warmer, and radiant floors. A neutral temp floor is all you need to negate cold tile discomfort. As a matter of fact. Neutral temp floors are all you will ever probably feel for the envelope detail of the home you are renovating.

So that gets you down to a two temp system. If you still want a towel bar warmer.

You are doing a sandwich style radiant panel with plates the best option as far as I'm concerned for getting the highest output with the lowest supply temps. As been said you can offset losses with tube density in your layout. To a point.

Remember you can size towel warmers, base board,and panel rads to use a lower AWT to keep things a one temp system.

Zman

The whole conversation about the floor "feeling warm" is an interesting one. With a tight well designed home, it is pretty difficult to maintain the warm floor feeling without overheating the house.
Siggy wrote this article which sheds some light http://www.pmmag.com/articles/83903-heating-a-thermos-bottle-house-br-john-siegenthaler

My house has radiant heat in gypcrete with a design day water temp of 120, controlled with outdoor reset. If I step on the tile and it "feels warm", it is always less than 10 degrees outside.
The rest of the time I am happy to have "not cold floors".

EPMountainMan

That's a really interesting article, Zman! With my fairly-well-insulated home, my avg. design flux is around 18, so my floors on average will likely feel like yours. Conceptually, I like the idea of concentrating heat into an area where one might really appreciate a perceived warm floor... at the exit of a shower or bathtub, standing at the kitchen sink, etc. Typically, such "striping" of floor temps would be discouraged in the overall design, but maybe if it is more intentional to concentrate heat in a few areas, then we might have a nice balance there.