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)

skimmer

I took some rough readings with a cheap laser thermometer. I got 175 at the end of the return before it goes back into the boiler. And 201 after the pump as it begins its run.

A couple of minutes later i got fluctuating readings of 150 - 159 at the end of the run.

The boiler cycles on and off, I guess to maintain water temp? While the circulator pump runs constantly.

Its about 56 degrees out. And no steam heat being called for the upstairs.

Jamie Hall

Sounds almost correct… the no heat upstairs is because the boiler isn't steaming. Is it being asked to steam? Or are you just working with the basement loop?

skimmer

No heat upstairs because we dont need it. There is someone staying in the basement room who has called for heat. So the boiler is cycling on and off I guess to bring it up to temp for the hot water circulation.

Just working with the basement loop. And it seems to cycle a lot

skimmer

Its a little tight! The sheetrock is removable when I need it. But as you can see the taco pump starts here and the copper begins its run out to the garage , thru the garage with about 18 feet of radiators, thru the basement room and back to the boiler,, maybe I need a new pump? a stronger pump ?

Jamie Hall

Based on those temperatures, you may not have enough flow (gpm). Have you figured the head loss on the piping and valves and compared it to the pump curve?

skimmer

No i have not. In the garage all the bare exposed copper is insulated. In one area where I am able to get to a radiator i can feel some warmth coming up and I can touch the radiator and the fins without it burning. This is about 10-12 feet away from the pump after the copper pipe goes under cement for about 5 feet coming back up into the garage. I don’t know what to make of this . I think it was ok years back but I don’t remember. Maybe it’s the flow? The pump?

the radiator I was able to feel

immediately where the copper enters the garage , it feels very hot here I think I got about 190 here and all bare copper has been insulated

unfortunately my garage is a mess and now most of the radiator and copper is difficult to get too

skimmer

after the garage it goes into a basement room. The rads get warm but I feel like they don’t get hot enough to satisfy the thermostat. I feel like they should put out a warm steady rising heat Maybe it’s me??

EBEBRATT-Ed

Your boiler is good for 271 sq feet of steam radiation which is 65,113 but that is for the steam radiation. Any hot water zone off the boiler must not exceed the boiler pic up rating. in your case the pick-up rating is about 21,000 btus. That 21000 btu is in addition to the 65113 the boiler can produce for steam.

If you have 18' of fin tube in the garage that is about 10,000 btus so the boiler should be large enough. You only need to circulate about 1gpm through the garage circuit to satisfy 18' of fin tube.

I would calculate how many feet of pipe and how many elbows are in the circuit including the length of the fin tube from the boiler through the garage and back.

But I would be looking at a bad circulator , air binding or some sort of restriction as any circulator should supply that small load. A bronze circulator is best

skimmer

i can hear the water circulating thru the pipe in the back of the garage…also i can test it by open the drain valve where it returns (i have isolation valves) but how do i know if the flow rate is proper?

Jamie Hall

"After the garage it goes into the basement room"

That's part of your problem. Not the whole problem, probably, but part of it. As the water goes through the garage fin tube, it cools. By the time it gets to the basement room it's a lot cooler — and so the basement room doesn't heat properly.

Correcting that would ideally put the basement room and the garage in parallel. However, that may be difficult. Reversing the flow through the loop, however, would get the basement room the hotter water.

skimmer

Yeah I was thinking about that, reversing it so the hot water goes to the basement first, then thru the garage.. The garage I could care less about.

LRCCBJ

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.

There is one caveat that you must understand when you are making anecdotal temperature measurements:

All distribution systems have mass. When you start the boiler and it warms to 180F, and you expect 180F at all the convectors (you have no radiators), you failed to provide sufficient time to get to equilibrium. The convectors warm quickly, however, you must wait until they all have achieved the highest temperature they will achieve. The first convector WILL achieve 180F on the inlet and an expected 175F.……….give or take……….on the outlet. Measuring anything prior to this point is useless.

The final convector will achieve 160F……….give or take…………..on the inlet and an expected 155F………..give or take on the outlet. Again, measuring prior to this point is useless.

If the boiler shuts down on limit while you are waiting to take your measurements, all of them are out the window as the supply will cool to an expected 160F before the boiler restarts and all of the above values are incorrect.

The data must be taken under steady state conditions for any meaningful opinions on your situation can be provided.

Clearly, your increase in the SWT to 190F is a proper solution IF you cannot maintain temperature in the space. We do not have any knowledge of that as the outdoor temperature has been way too warm for a proper judgment.

skimmer

I just realized the last time i flushed it (the copper loop) i did it wrong. So i just re did, using city water pressure and isolation valves.

Flushed it in reverse, from the return at the boiler out via a valve near the circulating pump.

very dark brown water until it ran clear

Now i will see if that makes any improvement

Long Beach Ed

I run a 30-foot loop with 15' of hot water baseboard off an IN4 steam system boiler. I use a stainless Taco 007 circulator for over fifteen years with no problem, carefully keeping the condensate clean.

Remember that if valuable basement possessions or junk is blocking airflow through the baseboard, it's putting out virtually no heat.

Depending on the control configuration, when the boiler is steaming the baseboard loop will be much hotter than when it is not steaming. If you have a high limit Acquastat controlling the loop, you may want to turn up the temperature.

skimmer

all is good heat works fine.

Sootmaster

Is it supplying and returning at the bottom of the boiler? If so, its just circulating the cold water sitting on the bottom of the boiler until its actually firing which stirs everything up.

What I do is pull from the bottom and return where ever I can mid way up. That keeps the water from flashing and cavitation in the pump when it's on a run for steam.

skimmer

no water comes back on one side leaves on the other.

skimmer

well yesterday the thermostat was set for 70 and the boiler ran for over 3 hours straight with the outdoor temperature being only 50 degrees. I think the 007 may be the problem

I have the Honeywell round. Any chance it could be the thermostat itself ?