looking for feedback on expanding a hydronic radiator system

[DIYNero]

Hello, I am attempting to alter an existing hydronic boiler system to accommodate a room that was enclosed after the building was built. I have been weighing a few different options, and i would like to avoid electric heat.

1) the interior radiator overheats the room it is in. not terribly surprising as it wasnt designed for this layout. I thought i may be able to add a tee in the existing piping, drill through the wall (masonry) and had a radiator on the other side. thinking is it would draw off some of that over heating while exploiting existing system. Downside is that wall is prime real estate in the room, and so reduces its usability.

2) Run piping along the wall behind everything to a small radiator in the room. While I am scared to cut into the existing system too terrible much, there is copper on the lines for the supply and return near the boiler. It wouldnt be in line with how the rest of the system functions (heated water is dispersed at same level in the floor and ceiling), to account for this i would had some shutoffs so i could adjust how much water is reaching the back unit. The radiator would be much smaller than may be needed, but as the thing has no heat at all currently would presumably make a big difference anyway. but, maybe wouldnt be sufficient no way no how, and then id be stuck with it.

3) build a short platform under the laundry to install a kick hydronic heater. Saves space, but raising the laundry isnt favorite, and ive never worked with a kick one, didn't even know they existed until i started researching.

Any ideas or feedback out there? i added a crude drawing for reference. the floor in the back is solid concrete, and is on the second floor, so i cant really cut into it.

 

[John Gayewski]

You wouldn't add a tee to your existing radiator. If anything you would add a coupling and heat the radiators in series. Meaning the hot water would travel through one radiator into the next radiator then back to the boiler. Adding a tee would be a way if you have room for ball valves to control how much water is going into each radiator but ball valves aren't the greatest for that.

Your existing boiler piping, how is it piped now? Series, parallel, two pipe, one pipe, primary secondary?

 

[Sponsor]

 

[Fitter30]

Normally fin tube/ radiators are piped on outside walls and under windows to offset the load. What water temp r u running? Coldest days of winter the boiler cycle off?

 

[cdherman]

1) The kick space heaters really annoyed me when I had one. The beauty of hydronic heat is that its silent and doesn't kick up dust. Kickspace sort of ruins that.

2) Can you clarify -- do you have radiators or slant fin style baseboard convectors? I know everyone calls a heater that uses hot water a "radiator" but its important to understand that baseboard convectors work best by getting warmed air rising via convection. They warm the air. Your drawing leads me to think you have convectors. Radiators on the otherhand have surface area that is hot to the touch. This literally radiates "radiant heat" into the surroundings. They also used to burn kids, especially in the days of steam. But with modern modulated hot water boilers, that's less of a problem.

Ball valves are big and cumbersome. Google "hydronic balancing valves" They come in a variety of forms. They don't need to be capable of complete stoppage of water. They just adjust flow rates in a parallel piped situation which is your #1 proposal. You *may* be able to get by with one, but you may need multiple. balancing valve

OR, you can install thermostatic heads. A thermostatic head (they are available both as analog -- uses wax like your radiator thermostat, IIRC, or newer are electronic. This is basically a valve that works similar to your balancing valve, BUT it can vary the balance on its own.

I had a house that was mixed in Boston. 1/2 was old ornate radiators, backside was baseboard convectors. And it had balancing valves. And things were never right. Too hot, too cold never right. I played with the screws to balance endlessly. Till I retrofitted the entire works with thermostatic heads. This system required me to install the valves and heads. A lot of retrofitting. I managed to used a hole saw to cut holes in the end caps of the baseboard to let the heads stick out. It worked really well, but I cannot say it was easy.

Your #1 solution could put a thermostatic head in the one room you say is already too hot. But you might be better off with therm heads on both of the baseboard runs. Each room can then get its own preferred temp.

To the best of knowledge, you MUST become proficient in sweating copper to do this yourself. Its best done by a DIYer in the Summer!!!!

Valve

Thermostatic head for valve

Finally, if wall space is valuable in the room where you are trying get heat too -- consider putting a real radiator in. It will work best with the thermostatic valves. But a real radiator can be placed in vertical orientation and throw off FAR more heat for a give amount of wall space.. European style radiators actually radiate heat AND convect heat via air at the same time.

European style modern steel radiator

One last bit of experience. So you want to run a return line somewhere along a wall and have it be discreet. And you cannot go up or down. Remove whatever you have for baseboard and if there is drywall or whatever, remove 4" or so of that too. Down to the masonry that you say you have. Now you attach 1" x 3/4" furring strips top and bottom. Between those strips you have a chase to run that return line. You get it all in place and then cover it with as thin of plywood you can find. Cap it with another piece of wood, routed with whatever profile pleases you, and it all looks like there are no pipes at all. Let me know if you need pics of this.

I am German so I am accustomed to hot water heat. On my second US house with it, and my brother here in the USA has steam heat. So I've become pretty knowledgeable. Hope this helps.

Edit: in the meantime another post notes that convective baseboard is best under windows or on outside walls. This is correct from an "comfort and efficiency" perspective. But life is what it is and sometimes you have to put your heat where its fits!

 

[DIYNero]

You wouldn't add a tee to your existing radiator. If anything you would add a coupling and heat the radiators in series. Meaning the hot water would travel through one radiator into the next radiator then back to the boiler. Adding a tee would be a way if you have room for ball valves to control how much water is going into each radiator but ball valves aren't the greatest for that.

Your existing boiler piping, how is it piped now? Series, parallel, two pipe, one pipe, primary secondary?

It is a two pipe system.

Tee, coupling, my mistake. My thought was to have two radiators share that water, reducing the heating on one side by forcing it to be shared between two room, which I think is what you are describing.

 

[DIYNero]

1) The kick space heaters really annoyed me when I had one. The beauty of hydronic heat is that its silent and doesn't kick up dust. Kickspace sort of ruins that.

2) Can you clarify -- do you have radiators or slant fin style baseboard convectors? I know everyone calls a heater that uses hot water a "radiator" but its important to understand that baseboard convectors work best by getting warmed air rising via convection. They warm the air. Your drawing leads me to think you have convectors. Radiators on the otherhand have surface area that is hot to the touch. This literally radiates "radiant heat" into the surroundings. They also used to burn kids, especially in the days of steam. But with modern modulated hot water boilers, that's less of a problem.

Ball valves are big and cumbersome. Google "hydronic balancing valves" They come in a variety of forms. They don't need to be capable of complete stoppage of water. They just adjust flow rates in a parallel piped situation which is your #1 proposal. You *may* be able to get by with one, but you may need multiple. balancing valve

OR, you can install thermostatic heads. A thermostatic head (they are available both as analog -- uses wax like your radiator thermostat, IIRC, or newer are electronic. This is basically a valve that works similar to your balancing valve, BUT it can vary the balance on its own.

I had a house that was mixed in Boston. 1/2 was old ornate radiators, backside was baseboard convectors. And it had balancing valves. And things were never right. Too hot, too cold never right. I played with the screws to balance endlessly. Till I retrofitted the entire works with thermostatic heads. This system required me to install the valves and heads. A lot of retrofitting. I managed to used a hole saw to cut holes in the end caps of the baseboard to let the heads stick out. It worked really well, but I cannot say it was easy.

Your #1 solution could put a thermostatic head in the one room you say is already too hot. But you might be better off with therm heads on both of the baseboard runs. Each room can then get its own preferred temp.

To the best of knowledge, you MUST become proficient in sweating copper to do this yourself. Its best done by a DIYer in the Summer!!!!

Valve

Thermostatic head for valve

Finally, if wall space is valuable in the room where you are trying get heat too -- consider putting a real radiator in. It will work best with the thermostatic valves. But a real radiator can be placed in vertical orientation and throw off FAR more heat for a give amount of wall space.. European style radiators actually radiate heat AND convect heat via air at the same time.

European style modern steel radiator

One last bit of experience. So you want to run a return line somewhere along a wall and have it be discreet. And you cannot go up or down. Remove whatever you have for baseboard and if there is drywall or whatever, remove 4" or so of that too. Down to the masonry that you say you have. Now you attach 1" x 3/4" furring strips top and bottom. Between those strips you have a chase to run that return line. You get it all in place and then cover it with as thin of plywood you can find. Cap it with another piece of wood, routed with whatever profile pleases you, and it all looks like there are no pipes at all. Let me know if you need pics of this.

I am German so I am accustomed to hot water heat. On my second US house with it, and my brother here in the USA has steam heat. So I've become pretty knowledgeable. Hope this helps.

Edit: in the meantime another post notes that convective baseboard is best under windows or on outside walls. This is correct from an "comfort and efficiency" perspective. But life is what it is and sometimes you have to put your heat where its fits!

They're not baseboard, they're heavy original cast iron radiators.

A real radiator would use substantially more space than the kick one. The kick one I can slip into existing unused space. Did you find the heating acceptable (after noting the complaint about dust)?

I only sweat copper when i plumb. Did a whole house last year, only one small leak when i was done. I'd say its one of my stronger diy skill sets.

Thanks for the insights on the valves, I will research those. I don't expect perfection, but having done in floor heat to deal with this problem previously id really like something that is actually part of the whole system.

 

[cdherman]

Did you look into the thermostatic heads and valves? This should perfectly work with two radiators working off one supply. They will allow different temps in the rooms and they will self regulate if the demands are different based on outdoor conditions (sun, wind, air temps). Fixed valves cannot deal with those variables. And it allows you on the fly to shut down the heat in one or the other room and direct more water to the other room, should your living situation require.

As for case iron baseboards, you are lucky. Those were and are still I assume very expensive, but they incorporate the best of both worlds -- they radiate, but typically they convect some too. Sited correctly under windows or on outside walls, they are also less intrusive that classic radiators.

Not as good as in floor radiant, but good enough.