Too much Head?

Ipumpaway

Hello All,
I am a home owner near Syracuse, New York who would like to ask the hydronic heating experts here to please take a minute to tell me where I may have gone wrong with my calculations, observations and assumptions below. I believe the circulator on my heating system may be too small for its job. I have calculated my flow requirement at 20 GPM and the head loss of the piping system at 13 feet of head. If I made my calculations properly a Taco 0012 will provide this flow and pressure.
Let me start by summarizing the current condition. The warmest room in the house is the unfinished basement where the boiler resides. In January and February it feels like it is in the upper 70’s to low 80’s down there. Meanwhile several radiant units in the living areas on the first and second floors do not heat at all. I believe most of the hot water is staying in the basement because the current circulator cannot overcome the pressure loss of the risers.
The house was built in 1949 with an oil fired boiler, free standing cast iron radiators and a B&G monoflo piping system. The boiler was replaced in 1984 and several free standing radiators have been replaced with cast iron baseboard units.
My wife bought the house from her grandmother in 2008 and her first winter in her new home brought about her first “no heat” service call. The call went out to her fuel oil supplier with whom her grandmother signed a service contract decades before. As long as she bought all of her fuel oil from the local supplier they would service the boiler and replace any faulty components for free. So my wife was very happy to hear from the service tech that he found the problem and replaced the broken circulator with a brand new one at no charge. The newly installed circulator was a Taco 007 model. I believe the original one was a B&G because of the red paint on the re-used flanges. But unfortunately it is long gone and I have no idea which model it was.
Here are my calculations for the longest circuit. This circuit leads to a small bedroom on the second floor where the free standing cast iron radiator does not heat at all. That is unless you bleed it for an hour. If you do bleed/drain it for an hour (no air comes out after 15 seconds) it’ll get nice and toasty.

Equivalent length of pipe of longest circuit;

¾” piping
6- ¾” 90 degree elbows (6 x 4.4’ each = 26.4’)
10- ¾” 45 degree elbows (10 x .9 = 9.0’)
25’ of ¾” pipe

The total equivalent length of ¾” pipe is 60.4’. Using a flow rate of 5 gallons per minute the water will move at 3’/second and the head loss will equal 6.4’ of head.


1-1/4” piping
6- 90 degree elbows (6 x 6.6’ each = 39.6’)
1-45 degree elbow (1 x 1.7’ = 1.7’)
5- 1-1/4 x 1-1/4 x 2” tees (5 x 5’ = 25’)
5- 1-1/4” Monoflo Tees (5 x 5’ = 25’)
53.5’ of 1-1/4” pipe

The total equivalent length of 1-1/4” pipe is 144.8’. Using a flow rate of 10 gallons per minute the water will move at 2’/second and the head loss will equal 4.5’ of head.

1-1/2” piping
4- 1-1/2” Monoflo Tees (4 x 5.6’ = 22.4’)
1 – Wye ( 1 x 6’ = 6’)
13’ of straight 1-1/2” pipe

The total equivalent length of 1-1/2” pipe is 41.5’. Using a flow rate of 20 gallons per minute the water will move at 3’/second and the head loss will equal 2.2’ of head.

So I then added up the head loss from the ¾”, 1-1/4” and the 1-1/2” sections of the longest circuit and came up with 13.1’ total head loss. That’s how I came up with 20 gallons per minute and 13’ of head which brought me to the Taco 0012 circulator.

Am I even close to doing this correctly?

Brian

Ipumpaway

Hi Hatterasguy,
Thank you for your reply. There are no zone valves. The supply side is a 1-1/2" pipe which runs across the basement and wyes into two 1-1/4" mains that run around the perimeter of the basement in opposite directions. They join at the other side of the basement and tee into a single pipe that enters the boiler on the return side. The 3/4" pipes are risers to and from the radiators. There are Monoflo tees at the supply risers and standard tees on the return risers.

Steamhead

I'd be willing to bet the old circ was a B&G 100. Like the Taco 110, this was a very popular unit. If the 007 fit the old flanges perfectly, there's a 95% chance the original circ was a 100.

The current Taco wet-rotor circ that matches the 100 is the 0010.

Ipumpaway

The piping looks a lot like this picture from B&G design guide.

Paul48

Follow Steamheads recommendation. Just for clarity....the Taco 0012 at 13ft head will pump 8 gpm.

Ipumpaway

Hello Hatterasguy,
The first monoflo fitting on the 1-1/2" main is the supply to a 14' cast iron baseboard in the living room right below a picture window. That units gets the hottest of the 9 radiators in the house. It is on the first floor directly above the boiler. The return for that unit is also the only connection to one of the two 1-1/4" circuits. The systems seams very out of balance. The main trunk has four other monoflo fittings going to two more radiators. I believe those radiators are on the second story. The remaining 6 radiators are one the other 1-1/4" circuit. You are right about the radiator in the small bedroom on the second floor that doesn't heat up. It is the second to last one on the circuit. The last two units on that circuit don't heat at all.

Ipumpaway

Hello Hatterasguy,
I don't know how the system worked with the old B&G circulator. My wife bought the house and the B&G failed the first winter she lived there. So when I asked her the same question you asked me she said, "I don't know". It may have worked great or it could have worked poorly from day one. I have found home owners will tolerate things not working right for decades. ????

Ipumpaway

I was thinking I would move the supply to the 14' baseboard off of the 1-1/2" main and place it where it should be, on the 1-1/4" main. I thought I might also add a gate valve right after the wye and ahead of the new supply Monoflo so I can regulate the flow through that circuit since it will only have one radiator on it. Will I be able to balance the two circuits a bit with a gate valve? Does that make sense?

Ipumpaway

Hi Hatterasguy,
Thank you so much for taking an interest in my heating system. I have taken a look at Dan's Q & A on Monoflo's. I also bought his book, "Classic Hydronics" and my wife teases me about how many times I've read it! I downloaded the Bell & Gossett design handbook from 1949 that Dan made available and I've read that more times than I'd like to admit. I can certainly see how you could spend a lifetime learning what makes these systems work and what makes them flounder.
I am worried about choosing a circulator that is too large. I don't want to be sitting on the couch in my living room, watching a football game while hearing water pounding through all of the radiators in the house. That would not be good !!!
I like your idea of putting in some ball valves and using an infrared heat scanner to balance out the flow. That will give me something to do at halftime !!!!!!!!!!
So just to make sure I understand you, are you suggesting I use the ball valves to slow down the flow of water through the 14' baseboard so the water will lose more of the heat it is carrying? The heat will be transferred into the living room and I will know when I have adjusted it properly when the water exiting on the return side of the radiator is 30 degrees cooler than the water entering on the supply side?
Will the amount of water flowing through the remainder of the system (the other 1.25" circuit) increase when I close these ball valves on the 14' baseboard circuit or will the flow through the entire system decrease? Trying to wrap my brain around what water does in these situations.

Ipumpaway

Thank you very much for your help. None of the other radiators in the house get hot. Even the very next one in the line after the living room baseboard doesn't. If I crank the thermostat to max so the system runs almost constantly for an hour the living room baseboard gets hot. The two farthest from the boiler do not heat up at all and the remains 5 get luke warm at best.
That's why I'm thinking I might want to go with the 0012 and add the ball valves on the risers. Unless you think the 0012 is really overkill?
The infrared laser heat guns look very affordable and will certainly make the adjusting much easier. I'll pick one up. Thank you that suggestion.
Could the radiator supply valves which are already in place be used for adjusting delta T? Or should I just remove those and add ball valves to each supply riser in the basement? The existing radiator valves look like they might really add a lot of restriction to flow.

rick in Alaska

Also, what is the system pressure the boiler is running at. With the house being two story, it does not want to be at 12 psi. More like 16 to 18. Could make a difference.
Rick

Rich_49

How large is this house and has any insulation work ever been done to it ?
Make sure you calculated your head loss properly also . See the following

http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/A-400C.pdf

Paul48

You have 9 emitters in the home? Please count them, to verify that no one has capped a monoflo circuit.

Ipumpaway

Hello Rick,
Thanks for you question about the system pressure. Last winter I observed the system pressure was 18-20 psi. I increased it to 25 psi for a few days to see if there would be any change. There was not so I lowered it back down.

Ipumpaway

Hello Paul48,
Someone did remove a radiator at some point years ago and did cap off the side branch of the supply Monoflo. I plan to remove that capped off Monoflo fitting this summer. I read in Dan's book that this is a real bad thing to do. Dan described it as a traffic jam up ahead with no way around.
Do you think I will see a significant change in the system performance once that one capped Monoflo is removed?

Brian

Paul48

It creates huge head, because all the flow is now forced through the orifice of the monoflo tee. It's like throttling the whole system.If you don't want to use it to feed an emitter, you need to pipe a by-pass.