how to plumb a radiator in the boiler room?

dronic123

My boiler room gets very cold when it gets super cold outside, even though the mid efficiency CI boiler gets really hot at the same time. I think it is because of the fresh air opening. It doesn't seem to me that the boiler itself throws off enough heat. I have the circulator going 24/7 but and I am worried about the domestic water pipes freezing as there often is no water movement in those pipes. So first of all, I thought about plumbing in a rad. Perhaps I could valve it off in the Spring and the Fall??

Supposing I had a really simple system: how should I do it?

Hot supply water into the rad first? or should it come first from the return?

Do I need a check valve? or perhaps just a regular ball valve with a check inside it???

Should it return to the supply side or the return side?

Should we/ do we need CSTee's—If so would we need a small circulating pump?

What about putting the tee's both on the same pipe but not closely spaced?

I would appreciate your thoughts.

Jamie Hall

Don't make it more complicated than it needs to be! Take your supply from the supply. Run it through a balancing valve (you're going to need that!) then through the radiator — it doesn't matter which way it goes — than into the return.

Have a shutoff valve and a unio for repair on both the supply and return.

Big Ed_4

Another option is Field's "Air in a Can" and close up the fresh air vent during the Winter …

dronic123

@Big Ed_4 The code seems very specific about sizing of the fresh air vent; would this "air in a can" complicate things?

dronic123

@Jamie Hall Thanks for the good tip about the unions and isolation (2) valves on the rad

I think I diagrammed——- taking from the supply and sending it over to the return—that way I can get the hottest water to the boiler room rad. How does a balancing valve work? Can you use a regular ball valve and adjust it manually?

hot_rod

Do you have high and low air vents into the room? Some installers pipe them vents down into a 5 gallon bucket to lessen the draft coming into the room.

It must be very leaky of a room if a cast boiler cannot keep it warm? That is all heat load to the building.

The pipe is a few inches above the bottom, no lid.

Screenshot 2024-07-16 at 7.42.11 AM.png

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1806276#Comment_1806276

Well, you can — although ball valves are not very good at controlling flow. At least better than gates. On an application like that, I'd probably use a plain old-fashioned radiator valve (they are a type of globe valve) on the inlet… or a globe valve on the supply line. I might spend the cash on a genuine balancing valve — they are designed for smooth and more or less linear flow control — but I don't think you need it for that application.

Mad Dog_2

Small Electric powered Unit Heaters with their own T Stat are perfect for mechanical rooms to keep pipes from freezing. Mad Dog 🐕

EBEBRATT-Ed

You only need fresh air when the boiler is actually firing. You can use dampers with the actuators wired to the boiler start circuit but you must have end switches on the dampers to prove they are open before the boiler can fire

pecmsg

what’s the make and model of this boiler?

dronic123

I only have one 110 V electrical 15 amp circuit in the boiler room and if possible, I don't want to compromise the boiler by overloading the circuit with any sort of electrical heaters. Similarly, I don't want to add electrical draw with a fresh air damper and I am also concerned the fresh air damper might fail in the closed position and of course, that could lead to a disaster. I already have one damper danger in the flue damper; no point in doubling the risk. At present, If a domestic water pipe froze in the boiler room, the damage would at least be confined to the boiler room.

So I think the extra rad is a good solution, particularly if the termination of the fresh air vent with a 5 gal bucket would control the effect of wind on the fresh air coming in. —-good tip!!—. I just need your help in installing the rad with the best possible pipe design.

@Jamie Hall the balancing valve, appears (from Supplyhouse picture) to be manually operated. Is the purpose to restrict the flow to the capacity of the rad so that you leave as much heat capacity available to the rads in the living sections of the house? Can you set the balancing valve once and not have to reset it throughout the year?? Can you shut a balancing valve right off so it can also act as an isolation valve or do you need one of those too??

If, for example, the EDR of the rad is 20 sq ft—- Would the BTU's per hour be 5,000? and if we connected the rad with a 1/2" copper pipe—-how would you set the balancing valve up? Is it a % of the flow rate of the pipe or an actual flow rate?

Thanks for the tip about the balancing valve. I would never have thought of it.

dronic123

@ hot_rod Thanks for the tip about the bucket

The fresh air vent lies close to the wall and it brings the fresh air down to 30" approx off the floor.

In the screenshot, it looks like there is a round duct and it's insulated? I was thinking of trying to heat up the fresh air as it was coming in somehow.

Is there a cover of sorts over the pail? I can't make it out.

Is the idea that because the air has to reverse 180* it slows down the "wind" effect?

So it's a good idea; I could probably fashion some sort of tall plastic box or pail.

But what about the code and the requirement to have a certain amount sq inches. Wouldn't that be clear square inches??

Yes the boiler room is leaky—but mainly the problem comes about when we get an exceptionally (and now less frequent, I suspect) cold and windy night(s) of -5F to -10F. The cast iron doesn't get any hotter in spite of the really cold outside temperatures, I am guessing.

I also should insulate the pipes; that would help—-but the question is how to plumb the rad if I wanted to install one.

Jamie Hall

The BTUh would be about 5,000 — if it were steam. Hot water — a good bit less (depends on water temperature).

Yea, the balancing valve can be used to shut the radiator off — but I'd find a setting which kept the area warm enough, but not hot, and just leave it.

Big Ed_4

You would need 1 square inch per 10k BTU appliance input of free air per vent , you need two vents if venting to the out side . Most are not up to code ..

You needs to supply enough air for combustion…

Your afraid of open vents during winter freezing water pipes in the boiler room…

Air in the Can are sized to supply enough for combustion .

Rather than installing a radiator and over heating the boiler room with total loss out the vent . It is another option….

Just thinking…

dronic123

@Big Ed_4 :hey big ed, thanks for continuing along with this thread. When you say 2 vents : is that the combustion air vent out and the fresh air in? or do you need one vent high and one vent low for fresh air for example. would there be any advantage, do you think, in splitting up fresh air vent? The opening in the wall is going to be approximately the same height above grade. The code seems very clear about the openings —-how does the big can of air get around them—do you think?

dronic123

@Jamie Hall thanks for continuing the thread. How does the balancing valve work? it looks like there is a gauge? a flow gauge? Can I be like a nerd and calculate the setting? When I really need the heat from this rad it will be exceptionally cold outside by definition, and the mid eff boiler is going to be blasting away at 180*F / 190*f / 200*F, and the rad, being first off the supply, is going to be the same temp. Quite frankly I will want all the heat I can get out of the rad to combat the extra cold air outside and the draft pulling it in to feed the combustion of the boiler. The radiators upstairs are going to be losing a lot of heat and the boiler is probably going to be firing more or less constantly. In the Spring and Fall, I could valve off the rad.

bburd

A non-electric thermostatic radiator valve could be a good solution here. However, you will need some kind of balancing valve as well.

Jamie Hall

Well… yeah, you could be like a nerd and calculate a bunch of stuff and get some meters on things…

Or you could just adjust the valve until you were happy…

hot_rod

in the town I worked in, a high mountain area, the AHJ approved 1/4” per thousand btu. A high and low vent of that size.

So calculate the area of any ducting you use to come up with 25 sq inches for 100,000 btu/hr boiler, for example. It can be any shape. A grill on the outside of course.

The bucket helps slow the convection of hot air rising and colder air falling into the room. It slows the air movement that is robbing the heat output from the boiler.

Grab the mechanical code book that applies to your area, if the room is large enough that counts as some combustion air.

Also your AHJ may have amendments to the sizing as my inspectors did, check with them.

If you add a radiator it can be a wild loop. That always gets some flow, or add a TRV. Most TRVs have a freeze setting, the snowflake logo on Caleffi brands, 40 F I believe

Big Ed_4

If from room to room 1 square inch free opening per 10K BTU in put . Out side to boiler room two 1" opening is needed per 10k input.