burnham IN4 steam boiler with hot water loop not enough btu's??

skimmer

I have a properly sized IN4 for my steam rads (replacement for an older original boiler many years ago) with a hot water loop to copper radiators for my basement..

Copper pipe runs starts its run thru the garage, which is all radiators , the enters the basement room again all radiators, goes thru a small bathroom one radiator, then all copper pipe back into the boiler.

I estimate 50 feet of radiator and maybe 50 feet of just copper pipe.

Taco circulating pump .

It doesnt seem to get hot enough.. Aquastat was set at 180 and the pipe at the return seemed cool all the time. So i raised the aquastat to 190 and the copper return pipe right before it blends into the steel piping of the boiler and it got hot.

But the rads just seem warm and not putting out heat like they should. I cant bleed the rads, but I can flush it the entire zone out with water so I do that to ensure there is no air in the pipes.

I just re read dan's article how to run a hot water zone off a steam boiler and i noticed it said something about delivering 40,000 btu/hr to the zone, thats good enough to heat a good size zone. Thats based on the net load of a 120,000 btu/hr and 1/3 pickup load being 40,000 btu

Now im wondering since my old boiler was inefficient and perhaps maybe oversized, could it be the IN4 just isnt up to the task?

According to Burham the IN4:

Max Input 105,000 BTU

DOE heating capacity: 87,000 BTU

NET I=B=R 65,000 BTU

What do you guys think? is it a btu problem? is the run too long? Do i have too many radiators? The people who installed this over 30 years ago I guess figured they might as well heat the garage since they were running copper thru it anyway. you can feel the difference in the garage in the winter ( and the garage is directly below the living room so it makes sense) but I am wondering if the garage radiators are stealing most of the heating energy. The garage has about 18 feet of radiators

EdTheHeaterMan

To be clear, what are you calling Radiators? Are you talking standing cast iron radiators or are you talking about the baseboard enclosures with a copper tube in the center of aluminum fins?

What is the Steam boiler's NET Sq Ft rating? That is the number you use to size a steam boiler. What is the connected steam radiator's EDR? You need to know that in order to get your answer here.

The next part of the equation is the BTU draw of the Baseboard (if that is what you are referring to as radiators that are using water) and what that zone might be taking away from your boiler. Based on a small output radiator like SlantFin 2000, you can expect to get about 360 to 380 BTU per lineal foot of element in a proper enclosure with an average water temperature of 150°. You have about 50 feet of radiator. That would be about 18,500 BTUh from your 65,000 I=B=R NET leaving you only 46,500 BTUh for the steam radiators if they both call for heat at the same time.

The thing is that when you are making steam, the average temperature of the water below the water line will increase to near 215° at the surface and perhaps 200° near the bottom. So your average BTU output per foot will increase to near 700 BTUh per lineal foot. That will rob 35,000 BTUh from the 65,000 I=B=R NET leaving only 30,000 left for steaming. You may have a boiler that is too small for doing both zones at the same time when you are near design temperature (Design temperature = coldest night of the year)

Jamie Hall

The other consideration is flow rate. To keep all that radiation happy, you are going to need at least 3 gpm through the loop. To see if that may be part of your problem, check the temperature of the water going into the loop and the temperature coming back (just checking the pipe temperature will do — no need to get fancy). If it's more than 20 F, you simply don't have enough flow.

ethicalpaul

Where are you located? I don't have all the math but a garage is freaking cold with a massive slab heat sink and probably crappy insulation. That could be a lot of BTUs as they said above.

The guys above are concerned about your steam heat in your house, but you don't seem to be asking about that…is the only issue you are seeing is that your garage water loop isn't able to heat your garage? Or is the house heating suffering at all?

skimmer

I’m located in NYC.
no complaints with the steam side. Everything is fine. I call for heat and I get it. System seems balanced.

the basement/garage radiators are the baseboard enclosures with the copper tube and fins fed by the taco pump.

I will check the temp difference as the weather gets colder.

it’s not that it’s freezing down there. The steam main runs right thru the basement room so we get heat from that when I call for heat upstairs. And I removed the insulation from that main in the portion of the basement that we use and the rest is insulated.

How can i describe it best. The radiators feel warm to the touch - the copper pipes- but I don’t feel the actual heat rising thru. The convection I believe its called? I don’t believe I get the warm heat rising even when we arent calling for steam.

Maybe it does in the garage at the beginning of the run I will have to check but my garage is a mess and getting to the radiators is a pain.

EdTheHeaterMan

This sounds like you have less than 3 GPM flow thru the baseboard. The temperature leaving the boiler room compared to the temperature returning to the boiler room will let you know that. No need to move anything in the garage. I just talked to someone on this site with a water zone off of the bottom of the steam boiler. Their Taco Pumps keep failing. That is because you both are basically operating an open system with lots of debris traveling thru those pipes and the bottom of the boiler. The Tac 007 and other wet rotor pumps are using that dirty water to lubricate the pump. If you are having trouble with circulation, then perhaps your pump is getting bogged down in some dirty water issues.

Is there a strainer on the inlet side of the pump to reduce the amount of crud that enters the pump? It seems that pros that do this kind of thing more often, prefer a 3 piece pump that does not depend on water lubrication. Some prefer the B&G 100 bronze body circulator. That is a real workhorse. Armstrong also has a similar pump that may be a little less expensive.

Check your ∆T on that loop before you do anything else. That will tell you the actual temperature at the end of the baseboard radiator. If it is near 140°F then that radiator is not putting out much heat. As the heat is in the first few feet in the garage (where you can get to because of all the stuff in the way). And regarding the stuff… is that stuff blocking the air flow thru the radiators in the garage? You may have a 95° section of garage behind all that stuff. Those radiators must communicate convection air to the rest of the room. Block the convection and you block the heat.

skimmer

Thanks Ed, I will do that. Last year I just did the hand test, very hot leaving the circulator pump and not so hot at the end of the run until i raised the aquastat wheel to 190. Meaning before I raised the temp I could hold my hand on the copper pipe at the end before it goes back into the boiler without it burning…

I didnt see a strainer inlet, I have to take a picture. The pump is more then 5 years old, it seems to be fine. I just flused out the the loop a few days ago, some brown water for a few seconds and it didnt look to bad

EdTheHeaterMan

@skimmer… just for reference Most folks can hold on to a pipe that is 120° or below. At 120° I could hold it for only a few seconds, and some even like their shower water to be a little above 120°.

So if you can hold your hand on the warm pipe, it is below 120° If you can't then it is above 125° That was one of my human thermometer tricks I would use to tell if something was at the proper temperature (to a point). Customers thought it was fake until I put a thermometer in the water and proved it was at 120°. (or higher, or lower)