IBC DC 20-125 Piping Diagram

firsttimedan

I want to install a new high efficiency combi system, with 2 zones (one fin baseboard loop and one cast radiator loop). I chose this model which is oversized for my heating needs for the 3.2 DHW GPM. I have completely rebuilt this house from the studs on my own and want to finish the job with this system. Where could I locate a thorough piping diagram to insure a safe and effective installation?

KC_Jones

firsttimedan said:

I want to install a new high efficiency combi system, with 2 zones (one fin baseboard loop and one cast radiator loop). I chose this model which is oversized for my heating needs for the 3.2 DHW GPM. I have completely rebuilt this house from the studs on my own and want to finish the job with this system. Where could I locate a thorough piping diagram to insure a safe and effective installation?

Why would you want to do this? Why not use a boiler with indirect tank or a separate hot water heater? The primary function of that piece of equipment is heating the house. You could quite possibly get equal or even more DHW with a properly sized indirect tank off a much smaller boiler.

If you oversize too much you will end up having to add a buffer tank to get it to run even reasonably well, so any space savings you may have gotten from that equipment is out the window.

If you rebuilt the house and have upgraded insulation and windows that boiler would (roughly speaking) quite nicely heat about 5000 sq ft. Unless you have a mansion I would suggest you reevaluate your plan.

As far as piping there are diagrams in the boiler manual, but I would suggest you educate yourself on hydronic heating before doing anything.

firsttimedan

Thanks KCJones. I got the suggestion for this boiler from the salesman at my local supply house. I have a well insulated 1,400 sq ft house with all new windows and doors. I now see that this will need a lot more investigation. I have an existing electric hot water tank and a workman like Sears boiler that I will try to get through the winter with, as I research and design my new system. what are the advantages of a boiler with an indirect tank over a boiler and an on demand DHW heater?

KC_Jones

First you need to do a complete heat loss for the house. This pretty much dictates everything about the system you are installing.

The advantage is efficiency. The combi at 125k BTU is probably at least 4 times the size you actually need for that house. Even with modulation you are huge. Think of it this way if your heat loss is actually something like 30k btu that is on the coldest day of the year. That combi would meet that requirement at close to the bottom of its firing rate. You want something that can modulate much lower.

Don't forget those types of boilers operate at peak efficiency with low water temperatures so you would need to look at your emitter size relative to the heat loss calculations to see how low you can go. When it's milder it shouldn't be a problem it's really just a question of how often you can run low water temps.

If you can't ever run low water temps the mod/con boiler the efficiency gain over a standard boiler becomes less. That is highly unlikely in my opinion.

firsttimedan

What do you mean by low temperatures? I've calculated my heat loss on the coldest days at about 25,500 btu. I have 30 ft of slant fin baseboard in the second floor loop through the bedrooms, and two monster cast iron radiators (me and another guy could barely lift one!) on the open floor plan on the first floor. The house is tight, with spray foam, taped sheathing, new double glass windows etc. I'm heating the whole house now in upstate NY with a basement woodstove, and its been freezing outside and comfortable inside. But I'd like to upgrade to a heating system that doesn't require me to feed logs every few hours! I am looking for simplicity and efficiency, which was the salesman pitch for the IBC DC combi. It seems like separate boiler/hot water might be better, as there are 4 of us in the house, and our hot water needs are disproportionate to our heat needs.

Leon82

The point of the condensing boiler is to have low return water temperature to condense the exhaust extracting the most heat from the burnt gas.

Running it like an iron boiler it will never condense. So the fin tube usually needs higher temps than the big iron rads.so you will need to plan for this in the piping

hot_rod

But also the hottest supply is only needed on the coldest day, in most areas you are at design condition less that 20% of the heating season.

So 80% of the heating season the boiler can run lower temperature and still meet the load. That is the beauty of a properly set outdoor reset control. It will supply only the required temperature, on some days it could, and will run 130f supply or less.

Also the amount an size of heat emitters will determine how low you can run, even on design.

I have some cast radiators and they never see above 130F, a nice slow even heat if you can keep them running all the time with just the right supply temperature.

It may take some experimenting to dial all this in, chose the lowest supply on the coldest day to maintain the home and build the reset curve from that point.

Additionally you could add or upgrade the fin tube to higher output style and allow it to run at low SWT also.

It is an odd mix fin tube and cast rads, completely opposite heat emitters, but doable with some tinkering.

kcopp

The IBC DC is a great little boiler. Yes by going w the combi version you are oversized on the heating side by just about any combi that is worth anything will do that.
Would using the HC version of that boiler w/ a 40 gallon indirect work better? Sure. Here is a link to the piping diagrams.

The install manuals are available at the website.

They also have a manifold that makes the primary secondary piping a lot faster.

http://ibcboiler.com/resources/concept-drawings/