Hydronic versus NG

[dbsoccer]

I'm in the planning stages of adding 350sqft to my 650sqft garage (located in northern Colordo). I'm currently fully insulated and plan to do the same for the addition. My current garage has portion of 10ft ceiling and a portion that is vaulted. My addition could be either flat or vaulted depending on how it is framed. My only source of heat thus far has been a hydronic unit heater as I have HW heat in the house so adding another zone was easy.

I've never been happy with the performance of the hydronic heater so am considering NG. But then there may be other factors at play, as volume versus sqft, when sizing the heater. I'd think a 45kBTU hydronic unit would be the same as a 45k NG but then I have no experience to make such a comparison.

Doe anyone have any experience with hydronic heating - successful or otherwise?

 

[75gmck25]

Your question is a little confusing, since many GJ folks use NG hydronic heat, not one or the other. However, I assume you mean you want to use some other type of NG heater (forced air, radiant, etc.).

Since you live in an area that needs heat for several months, you need to decide how frequently you will heat the garage. Keeping it heated all the time will cost quite a bit, but makes sense if you are using it every day for work. Heating it only when you need it will be much cheaper, but it will take a while to get it to a comfortable temperature.

If the hydronic heat is in-floor it takes a long time (all day?) to warm up the slab, but its great once its warm and it will hold heat for a long time. If you use hydronic finned heaters or radiators it will heat the air faster, but may still take several hours to get the garage warm. This means that hydronic is probably not the right choice if you want to turn off heat most of the time to save cost, but come home every once and a while and work in a warm garage. For infrequent use you might want to use a radiant heater, forced air, or some other heater that will bring the temperature up quickly. All of these heaters can run off NG if that is what you have available.

Bruce

 

[dbsoccer]

Thanks Bruce. Sorry for the confusion.
By NG I meant a radiant heater such as the Modine Hot Dawg that has its own NG supply and vents through the roof/wall. I wanted to compare that to a hot water unit heater that would, again, hang from the ceiling like the Hot Dawg (and with a fan) and would be supplied with hot water from the same NG fired boiler I use to heat the house and domestic hot water. I have a priority control system, using a series of relays, that allows the current hydronic garage heater access to the boiler's water only if the domestic and house heating needs are met. So, yes, I'm considering a larger hydronic unit heater (finned with a circulating fan) instead of a similar NG fired unit.

I'd like to be able to work in the garage during most days after I retire. BTW: Colorado winters may not be as long and cold as you might think. But then it's all what you're used to, I guess.

 

[Pointbock]

What size is your current unit (btu's)?

 

[csp]

A Hot Dawg is forced air, not radiant. Hydronic is one type of radiant.

 

[Shop Specialties]

So you have a 45K BTU hydronic unit heater pulling hot water off your house boiler heating 650 sq ft. Is that correct ?
Then you have a control that only supplies hot water to it if the house is satisfied ?

I am guessing since you have that control your boiler is not sized big enough to do everything ? If that is the case I would stop right there with the hydronic unit heating. The 45K should be more than adequate to heat 650 sq ft.

 

[jav]

Dbsoccer- not an expert but I have a little experience with this.

1st- BTU's are BTU's regardless of how they are supplied (hydronic versus NG). You may be getting confused because many heat sources are rated for a certain BTU but they may specified very differently.

For example- many NG heaters, hydronic or forced hot air, are rated at input BTU. However- the output BTU is likely very different and based on the units internal efficiency as well as delivery losses.

Many Hydronic unit heaters are rated at a certain capacity but only with a very specific temperature AND flow of incoming water. If you don't have that temperature and/or flow- your output will be different.

Lastly- understand that much of todays BTU demands/recommendations are based on a dwelling unit where your adjusting temperatures a few degrees from a prior set-point. Garages tend to see greater swings in temperature so you no only have air temps to bring up- but a lot cold soaked mass which not only puts greater demand on the heating equipment- but also effects your received comfort in the reheat process.

 

[Bondo]

I'm in the planning stages of adding 350sqft to my 650sqft garage

Ayuh,.... 1st step is learnin' the terms yer usin',....

Yer title is way beyond confusin',...

Hydronic is hot water heat,...

NG, as far as I know is Natural Gas, a form of reasonably portable energy,....

You can heat yer hot water with NG, so ya can't compare 'em, comparison is irrelevant,...

I'm guessin' yer talkin' 'bout a hot water radiator, vs: blown hot air from a natural gas appliance,..??..??

Anyways,..... I suggest ya lay pex tubin' in the insulated slab yer gonna pour, 'n go Hydronic Radiant heat,....

Fire the boiler with whatever energy type ya want,....
Gas, Oil, Coal, or My preference, Wood,....

 

[dbsoccer]

Jav, you are correct. BTUs are BTUs independent of the source. The primary difference I have found since starting this investigation is with the delta T between incoming and outgoing air. The exchanger in the hydronic unit can be no hotter than the water hence no hotter than 200F and most likely significantly colder (~175F or less). The exchanger in a gas fired unit heater will be much hotter and, as a result, the delta T will be wider. This might provide for a faster warm-up, etc.

Bondo, I'd like to have radiant floor heat but unless I jackhammer up the entire garage, I'd only have in in a third of the space. And then there is the matter of the water temp. Radiant floor heat uses water temperature much lower than a convention domestic baseboard residential heating system. There is no ROI in making the switch.

While I somewhat admire your back to nature preference to burn wood, we can all be glad that we now have NG as our primary energy source.