Hi all ....Does anyone have any advice on hydronic radiators ....how well do they work, what to buy, how should they be piped in, should they have their own control thermostat etc. Thx again, RH
1) Hot water baseboards - finned horizontal pipe units
2) Old-fashioned cast iron free-standing units
3) Hot water radiant wall panels
There are a few other variations, but it would help to know what you’re thinking of, a little bit about the building (size, new or retrofit, heat load), heat source, and so on.
I want to heat the upstairs of my farmhouse with them ....about 350 square feet. And then I also need to provide heat to a bathroom and utility room ....both about 100 square feet each. I am going to put radiant floor heat in the downstairs of the house ....and will also have a heat exchanger in the forced air ....but due to the existing ductwork being between both floors ...I am concerned about the downstairs getting warmer than the upstairs and would like to depend on the forced air as a last resort. Thx, RH
Others will doubtless chip in, but I think that standard baseboards are the easiest retrofit. They don’t take up any real floorspace and are minimally disruptive. They come with shutters that can be used to reduce output.
The output varies by brand and model, but they’re usually in the range of 600 BTU/ft/hr. There’s a spreadsheet that’s mentioned on another thread somewhere that allows you to plug in constructionl, weather, and window data and get a heat load per room. This is a good starting point and can help you get a rough idea of the baseboard needed. If you’re heating with wood, you might want to increase it if possible to allow satisfactory operation at lower temperatures.
Baseboard can be installed with normal copper plumbing or with PEX (much cheaper, easier to snake through existing construction in some cases).
You didn’t mention your heat source, but you’ll need a boiler of some sort with circulator(s) and possibly zone valve(s) as well. There are several schools of thought on circulation and plumbing, but a lot depends on what you already have in place.
I will be using an OWB as the boiler .....so do the baseboard radiators need any kind of control mechanism or do they normally allow for reducing or exdpanding the amount of heat coming from them individually ...Thank you, RH
I heat a big, old farmhouse with 15 cast iron radiators and I’m very happy with their performance. They can be sized for the room they’re in, and you can add controls to fine-tune your needs. The nice thing about cast iron rads is they’re relatively cheap (around $100 each for used ones around here), and they look great with a fresh coat of paint. In a way, it’s like having a little woodstove in every room. You can warm your body parts by sitting or leaning on them. And, they perform better at lower water temps than baseboard, and hold their heat long after the circulation stops.
The downside is they are very heavy, so installation can be a bit of a challenge without the right moving equipment or sufficient musclepower. They hold a lot of water (that’s good), but you need to size your expansion tank accordingly. And, they eat up some space. I happen to think they’re beautiful, but that’s a matter of personal preference.
For cast iron rads or baseboards, you can get control valves called TRVs that allow you to independently set and regulate the temps for each radiator, if you get the piping right.
Hi Eric ...can you give me an idea of the cost of the TRVs? And maybe a source for them? Also, with the old cast iron radiators ....how hot can you run the water in them? Is a mix valve needed? Thx again, RH
It’s been awhile since I bought any, but they’re not prohibitively expensive. Any good heating supply house can provide them. Personally, I don’t think they’re necessary, but I like a nice, hot house.
You run system water through the radiators, so whatever the temp of your water is, that’s what goes into the rads. No mixing valve needed. They are effective down to 120 degrees, so if you wanted to put a big mixing valve on the main supply line, you could do that. Ours routinely run with 180-degree water. I’m not sure what the surface temp of the rads is at that temp, but it’s never too hot to touch.
Hi Eric ....My confusion is ....what determines hot water going through the radiators and creating heat ....or better yet how do you stop heat coming from the radiators if you do not want it? This could happen on milder days when the upstairs of the house possibly does not need heat radiated by the radiators. Do you basically put shotoff valves on the line running to the radiators? As always I appreciate it ....RH
There are a number of different ways to skin that cat, including the TRVs. Another approach is to zone it so that separate pumps or zone valves serve different groups of radiators. In my house, for example, I have two radiators each in the sunroom and the kitchen. Thermostats in those rooms either turn on or shut off the pumps when they reach temp. The radiators keep emitting heat long after the pump shuts off, so you get a nice, even heat.
If I was doing it that way from scratch, I’d make an upstairs zone and a downstairs zone, at minumum. You also need a distribution system that allows for even heat, i.e., each rad branching off from a main pipe on each zone. Otherwise, if you try to pipe them in series, the ones at the end of the run are always cooler than the ones at the beginning, and you can’t get an even heat out of your zones.
Panel radiators are a favorite topic as well as a favorite heat source for me. I sell them at both the retail and wholesale level, have installed them in many different applications and in many different methods. They are probably the easiest form of heat to install, the simplest to operate and provide a comfort level on a par with radiant floor when done right. They can be zoned as a group, like a baseboard system or you can zone them individually with a TRV (thermostatic radiator valve). Panle rads come in a multitude of sizes and about any color you would want is available. I love grabbing a nice warm towel off the towel rad in the bathroom after a shower. My own humble opinion is that panel radiators are the least understood and most often overlooked form of heat emitter there is. Heat output per lineal foot of wall space can be 3-4 times that of baseboard. You can pipe them in series, parallel, reverse return or whatever method turns your knobs and fits the application. When you install a house full of panel rads running off a variable water temp system you will be living in hydronic nirvana. There is no simpler system than a single circ running as many rads/rooms as you want, each with individual temperature control. No zone valves, no circulator panels or relays, not even any control wiring!!! There’s a reason panel rads and radiant floors are the predominant form of heat in Europe.
How’s that for a mishmash of thoughts........
Go to http://www.hydronicalternatives.com to learn more and please feel free to PM me if you wish but be prepared for a lenghty conversation. (see the first line of this post)
Soooo Heaterman ...Thx for the reply on the radiators. Now ....I know the panel rads can be expensive. And it seems you are indicating that they are superior to radiant floor heat ....which I am planning on putting in on the main floor of my little farm house. So are you saying do away with the radiant floor and get panel rads throughout??? Thx, RH
Soooo Heaterman ...Thx for the reply on the radiators. Now ....I know the panel rads can be expensive. And it seems you are indicating that they are superior to radiant floor heat ....which I am planning on putting in on the main floor of my little farm house. So are you saying do away with the radiant floor and get panel rads throughout??? Thx, RH
Wellllllll...........I’ll qualify that a tad. Panel rads can provide comfort that is nearly indiscernible from a radiant floor if done right. The thing you won’t get as much of is the “warm floor” feel of radiant. A panel rad emits a large portion of it’s ouput in the form of radiant energy. The same type of energy as a radiant floor. This is in contrast to baseboard which has virtually no radiant output, only convective air flow. We did an addition and reheat for a customer two years ago which involved ripping out the furnace in the existing house, installing panel rads there and doing the addition, 900 sq ft in Climate Panel. FYI, Climate Panel is an above the floor radiant panel that is probably the best system going for a number of reasons. Both husband and wife made the comment that if they had known panel rads were so comfortable they would have skipped the radiant floor. I sized their panel rads to provide adequate heat with a max temp of 150* water in order to keep their gas boiler (Viessmann) in condensing territory for efficiency’s sake.
The boiler is able to deliver variable water temp to the rads based on outdoor air temp. In spring and fall they will idle down to 85-90* water temp and provide the heat needed. We have 12 rads heating approximately 1,800 sq ft in the house that are circulated with a single pump drawing 55 watts. There are no controls, thermostats, wiring, relays.....nothing. Just rads and TRV’s, constant circulation and a very comfy home.
Let me ask a question if you will........What floor covering are you going to install in the radiant floor area and is it above a heated space? That would probably tip me one way or the other.
There are panel rads that can run you well over a grand for only 6-7,000 btu output but the standard models I carry run from $200-$500 depending on size. A nice little bath rad/towel bar will go for $250. TRV’s are about $30-$40 depending on brand. You can spend from $4 for basic 1/2” inlet/outlet fittings to $60 for an isolation valve set with unions and swivels that allow you to drop the rad off the wall for painting and cleaning without disconnecting it.
And while we are on the subject of TRV’s........here’s the really cool thing about them and why a good panel rad system is sooooo comfortable. A TRV is a valve that modulates water flow to the rad by the function of a fluid in the valve body opening and closing the valve as it heats up and cools down/expands or contracts. What this does for the room comfort and what we call the MRT or Mean Radiant Temperature, is so simple and basic that you wonder why all heating systems aren’t designed this way.
Simply put the radiator is always “on”. The valve is always providing heat output proportional (key word) to the load in the room. Let’s say you have a rad providing heat to a room and it’s sitting there all nice and warm doing it’s thing and you introduce 8-10 people into the room. Within minutes the TRV “see’s” the extra heat in the room and begins to squeeze off the water flow until it reaches equilibrium again. Shutting off entirely if need be. There is no on/off cycling like a F/A system or baseboard with pumps or zone valves. Just nice steady heat in the exact amount needed to heat the space. An additional bonus is that there is virtually nothing to break or wear out with a panel rad system.
