Hydronic Air Heat in Brownstone?
I am mid-renovation on a 1905 Park Slope double duplex brick townhouse and am having a central A/C duct system put in. Palone Bros have suggested we install a hydronic air heat coil so we can get our heat through the ducts as well. (Not ‘forced air’!) This way we can have a separate thermostat…
I am mid-renovation on a 1905 Park Slope double duplex brick townhouse and am having a central A/C duct system put in. Palone Bros have suggested we install a hydronic air heat coil so we can get our heat through the ducts as well. (Not ‘forced air’!) This way we can have a separate thermostat from the lower unit (we’re on the upper unit) and, perhaps, remove the radiators once we know we’re getting all the heat we need… Anyone who knows this system first hand please let me know your thoughts! (Mrs Limestone are you out there? Your reno blog on BS mentioned you were installing this system… Wonder how it worked out?)
You can regulate the flow of hot water through a radiator using common shut off valves. Steam being a gas which then turns to liquid, is less cooperative. To regulate the flow of steam in a 1-pipe radiator, you have to control the rate at which air is vented. Thermostatically operated valves do a good job of this though with some degree of room temperature fluctuation.
Master Plumber – In steam heat, partially open valves often leads to leaks at the radiator/supply pipe connection. Does the same hold true for hot water?
If it were a steam system, another suggestion might be thermostatic valves on the radiators. They replace the pressure release valves and vary the amount of steam allowed to enter the radiator when the heat is on. The more steam allowed in, the faster the radiator heats up and provides more heat to the room. Conversely, as you describe above, reducing the amount of steam being delivered to some radiators can increase the amount going to others because of the pressure differential. There are also low tech options like vari-valves which essentially do the exact same thing without the thermostat. I don’t know if there are similar options for hot water, but I’m sure Mr. Master Plumber can enlighten us here.
Hot water heating systems are very flexible and adaptable to changing heating demands. There are any number of heating controls available to customize and fine tune the way the water is heated and distributed.
You say you are in mid-renovation. Quite honestly, this is kind of late in the game to be trying to sort this out now considering how many options you should be looking at.
Has anyone mentioned adding an outdoor reset control, like the Tekmar 260, to modulate the water temperature through the system? It could save you 25% on fuel usage and effectively takes the bad thermostat placement out of the equation.
Thank you Master Plvmber, for your knowledge, and thank you bklyndoug for your first hand experience.
I am still on the fence: I am now being led to believe that we can balance the heat in the house by partially closing the radiator valves on lower floors so less hot water goes through those radiators and more hot water (or hotter water) can get up to the higher floors. If we can find a happy medium this way we won’t need the extra heat boost from the hydronic heated air and skip complicating the system. (and save the money)
Any thoughts on my chances of succeeding in valve tweaking of the hot water rads?
Also, perhaps by moving the thermostat from the 1st floor to the 2nd or 3rd floors (the middle of the house) it will be easier to get the house into equilibrium?
Like most things mechanical, hydro-air is fine when well-designed and applied.
The heat it delivers is often more gentle than traditional forced air because of its lower temperatures and higher relative humidity.
You still have to do the duct cleaning and supplemental humidifier thing, and that on/off feeling that you don’t get with radiators can be annoying…but it’s not a bad way to heat a building at all.
One interesting comparison: it takes a 1″ diameter pipe to deliver the same heat as a *standard* 10″ x 10″ duct.
I just went through this in the fall. I own a 1917 craftsman style house in the burbs. It had a single zone of heat (hot water rads) for a 3 floor house, with the thermostat on the first floor. We froze our asses off last winter because the thermostat on the 1st floor would be satisfied before the hot water made its way up to the rads on the upper floors. The 2nd floor would get some heat, while the rads on the 3rd floor stayed cold all winter. I needed to establish a new zone of heat for the upstairs floors.
Luckily, the prior owners had installed a Unico high velocity system that was AC only on the 2nd and 3rd floors. I met with an HVAC expert and he told me the best way to create a new zone would be to use the existing Unico system by adding a hot water coil to the air handler in the attic. Basically, this involved running a hot water pipe from the boiler in the basement up to the attic where the air handler was, and snapping a hot water coil module onto the existing air handler.
It took about 1.5 days of work to do. I had them remove and cap the rads on the 3rd floor since they didnt work anyway, but left the ones on the 2nd floor since I was concerned that the hydronic system would not deliver enough heat.
Well, I should not have worried in the least. That system CRANKS out heat – at 90 degrees plus from the duct. It also heats the 2nd and 3rd floors incredibly fast – you feel the difference in just a few minutes. I was able to efficiently add a second zone for about $6K by using the existing Unico system, and it works so much better than the rads. I can also take out all the rads on the second floor now, which frees up lots of wall space.
I am totally glad I did this and would recommend hydronic hot air without hesitation.
>I’m certain the poster means “not forced air” in the traditional sense. This system is called hydro-air.
Aaah, thanks. Nice to know the marketing hype distinguishing ‘real’ from ‘pseudo’ forced air ;).
Surprised no one has given the OP grief about using Palone for something fancy like this. I wouldn’t use them again after they thoroughly screwed up a package unit I had them install.
Master Plumber,
Thanks for the clarification. In your experience, is this sort of heat sufficient? My guess is no.