Will a modern Panel Radiator work with a Gravity System?

TheUpNorthState88

Hello everyone.

I’m currently having my home rewired and we are finding “stuff” that was hidden behind wood paneling so I’m at the point where I’m want to take things to the studs, insulate, and put up drywall. This one room is the only one currently heated by hydronic baseboard, I want to replace it with a panel radiator. They never ran enough length of baseboard in this room so it has never has heated well enough. That’s another thing that is pushing me to switch to a properly sized panel radiator. I will need 7500 Btu to heat this room properly.

Here’s my main question, will a panel radiator work with an original gravity system (*edit* I have no circulator pump, system is full gravity flow)? The baseboard, while not enough length, does get hot and provides warmth. This room was even used by the previous owner as her main bedroom. My system heating plant is my 1937 Ideal Boiler No. 7 so plenty of capacity to handle the extra radiator.

There is only one single zone in my home, the rest of the home is heated by cast iron radiators. I would LOVE to rescue a cast iron radiator from off Marketplace, but I’m on a budget as this room project was not originally planned for right now, this was only suppose to be about rewiring. But old homes reveal secrets when you start opening walls. So a panel radiator is much cheaper to buy, move, and install but still get needed output.

Here’s a pic of the current baseboard/room and what I would like to replace the baseboard with.

**fyi - (click my name and you can find my previous post months ago about my gravity system for those who want even more back details)**

Thank you all for your insights!!

Ironman

Not enough info.

Is the system still gravity flow or is it pumped? In either scenario, you would need to add a pump on the branch going to the panel rad, but that could disrupt flow to other rads if the system is still gravity.

I don’t understand your statement about a panel rad being cheaper than a cast iron. A used cast iron would be far less expensive than a panel rad large enough to produce 7k btus and wouldn’t require the addition of a pump.

TheUpNorthState88

https://forum.heatinghelp.com/discussion/comment/1814227#Comment_1814227

Full gravity system. No circulator pumps.

As for the cast iron rad, it is more expensive as I would need to rent a pickup, get multiple friends to assist with picking it up, and getting it up the stairs with more rental equipment. I would need one with at least 8 sections which easily would be 300 LB+. Versus, ordering one of these more lightweight panel radiators that can easily be shipped to my door and carried up by myself.

Ironman

You can rent a pickup for $30 and two men with a hand truck can move the rad.

The cost of installing a circulator and buying a panel rad that’s large enough will be be north of a grand just for materials.

hot_rod

the bigger or wider the passageway in the heat emitter, the better the flow- the higher the heat output

Looking at most panel radiators, the connections and passageways are very small compared to most iron radiators

Jamie Hall

The short answer is it is very unlikely to work satisfactorily, if it works at all, unless you put a pump on the lines going to it. And if you do that, you are going to have a really interesting time trying to get anything like a balance with the rest of the system — unless you put pumps on that as well.

TheUpNorthState88

https://forum.heatinghelp.com/discussion/comment/1814243#Comment_1814243

Even though the current baseboard operates with no assistance from a pump? I’m actually shocked the baseboard works but it does and no issues with the rest of the system either which led me down this inquiry.

delcrossv

https://forum.heatinghelp.com/discussion/comment/1814244#Comment_1814244

A baseboard is a 3/4 straight pipe. Not much restriction there.

mattmia2

Castrads makes some steel radiators that would probably work but those won't be cheap. You could use a couple smaller salvaged CI radiators.

Part of the reason this room doesn't heat well is because baseboard fin tube heats and cools quickly whereas cast iron will heat slowly and stay hot radiating heat for a while after the cycle ends. You will never be able to balance fin tube and standing cast iron on the same zone.

If the radiators in the other rooms are oversized you will have to oversize the radiator in this room by a similar percentage so that it will heat this room in the same length heat call as the other rooms are heated.

jumper

I knew a rather tall house that used gravity and panels. Rich guy's mansion. It had overhead distribution. Cannot remember for certain but I think each panel had its own supply from attic. Also can't remember what water temperature was used. I do remember that panels were on opposite wall from outside.

Ironman

https://forum.heatinghelp.com/discussion/comment/1814457#Comment_1814457

Not to be unkind, but I really don’t think that this applies here, because water takes the path of least resistance and it’s gonna find its way through the large 2” push nipples of the cast iron rads rather than the small tubing and flow setter of a panel rad. What you’ve described had all panel rads and therefore equal resistance.

Kaos

The way you can get more flow is by having a top supply and bottom return. This puts the internal passageways in parallel and although they are smaller, it will still flow reasonably well.

The other thing that helps is to use a taller rad, the extra height makes a big difference in convective flow rate.

Don't use any TRVs or small port valves.

This still doesn't solve the low mass issue but you should be able to get more heat there.

Instead of throwing more heat, sometimes, the easier option is to insulate and air seal the room, you can probably cut that 7500BTU down by 1/3 to 1/2 and would let you keep the existing rad. More elbow grease but lower cost and you end up with a much more comfortable space.