High delta T, how to adjust it?

icesailor

Flow:

There's no substitute for Mo FLo. Until it gets loud and objectionable.

Gordy

System psi

Has the fill pressure been checked? Should be 12 psi if one to two stories. If the fill valve has been closed, and the vents on the air scoop are open it's possible the system pressure has dropped do to air removal. This would effect flow if system pressure is low enough.





Does system have a bladders style tank, or gravity tank?



How old is the system? Is the circ original, or has it been replaced?





How are you measuring temps? Infra red thermometer, or other. If infrared are you shooting a non emissive area?





If you are supplying 180* water, and returning 120 the btus are getting off some where, and its not sounding like the baseboard from your description.

icesailor

Why:

Why does a gravity hot water system work with great big pipes?

You don't need a circulator. There is almost no resistance in the great big pipes.

You keep comparing an open loops like a domestic water system with a closed loop heating system. The only part of an open loop system that comes into play with your scenario is with hot water recirculation. If you have 60# static pressure in the system (street pressure) you don't need a pump that will overcome 60#. The hot water feed pipes from the hot water source are large and provide little resistance. The return is usually 1/2" and there is where the resistance is. But you don't need some huge pump to do the job.

Friction loss is as flow pressure differential. It is NOT the same as static pressure.

icesailor

Support:

It doesn't support the weight of the water.

You keep comparing total pressure with static pressure.



Total pressure is the total weight of the water on a gauge at the base of a column of water. Static pressure is the amount of pressure shown on a pressure at the base of a column of water.

A 4" pipe, filled with water has 4 times the volume and weight of water than a single pipe. But it will still only show 54.25. If you have four 2" pipes connected at the bottom, filled with water to 100' high, all gauges will still show 54.25 feet. And the total weight of the water between the 4" pipe and the 4-2" pipes will be the same. Connect to pairs of 2" pipes at the top and have the pipes filled to the top. The pressure doesn't change. Put a 007 pump on the bottom of either side of the loop. The pressure will not change. Turn on the pump.A 007 is rated for over 50#. It will circulate.

At least that is what I remember they wanted us to know when I took my Journeymans and Master Plumbers license, long ago.

The three most important things to know.

1:  2.31, the height in a column of water supported by 1 # PSI Gauge pressure

2:  .434 The amount of pressure that one foot of water exerts on a pressure gauge.

3:  The Square Root of Two. ( 1x1+1, 1x1+1, 1+1+2, the square root of two in 1.414.)

IMO

It is said that there are only five things that are only five things a plumber needs to know. Hot's on the left, cold's on the right, stink goes up, chips flow down, and payday is whenever you get paid. I submit that there is another. The Square Root of Two.

icesailor

Third world flow meter:

Gordy,

Ever tried my patented third world flow meter? I call it a step meter.

With the main at room temperature, turn on the circulator. Walk along the supply as fast as you can walk when you can't hold your hand on it. I rate it in how many steps per minute. Sometimes, I can't walk fast enough. Other times, it doesn't flow. Usually it needs a purge. Sometimes, I need to raise the pressure. I never trust boiler pressure gauges. I've seen too many gauges where I let water out of the boiler and the gauge was on 15#. When I added water to the boiler, it went up. So, was 15# equal to zero? Probably. What happened when I cranked the pressure to 35#? Nothing. It sure purged well. And compressed the air.

gennady

Sure

Thanks for information. We all learn from the best. I still have to learn what is static pressure and its difference from weight. Also I will write down thingis about hot and cold water. Thanks. BTW total pressure is the sum of static pressure and dynamic pressure. I remember it from hydrolic course in university I graduated 30 years ago.

gennady

Duplicate

Duplicate

icesailor

Bypass:

Shut off the by=pass so the water doesn't bypass. Your problem will go away. If the mains get hot in ten minutes of running, you don't have a problem.

icesailor

Average:

Gennady,

I'm not one of the best.

One of the questions on my Journeymans test 19 1967 was this. It all cover what you are dealing with.

What is the total weight of a 4" XH soil stack that is 50' high, filled with water at the base of the stack?

What is the total pressure (That would be gauge pressure) and the weight of the water.

You need to cpomute how many gallons of water are in the stack (Dsquared X H X .0034). How much does the water weigh (8.33# per gallon). How much does the XH cast iron weigh, how many joints are there (5' lengths), how much does the lead weigh (a pound per inch) and how much does the oakum weigh. 1/6th the weight of the lead. It is all related.

Tom_133

Icesailor there is a 6th thing!!

Early plumbers need to be taught the sixth and very important rule:



Don't chew your nails!!!



Worked with a guy who claimed my van stunk like fish, turns out, thats what the garbage disposal he just worked on had in it! He could smell it because he was chewing his nails.



Maybe the rule shouldn't be a plumbing rule, more of a rule your mom taught... wash your hands!!

Gordy

Third world flow meter

Yes ice I have, and that will get it close to trouble shoot. And yes to the pressure gauge reliability.



A lot of unknowns still in this thread.



How old system is.

Did it work before.

Was there always a 007

icesailor

Clean hands:

I have a box of Nitril gloves in my truck. XL, universal ones. I get them from an auto parts store. Because I work on oil burners, I've been told it is unwise to let the oil residue on your hands. The nasty chemicals can be absorbed through the skin. Never a good idea.

I hate changing dead disposals. They are always nasty and stinky. And they stink up the truck until disposed of. That's why I carry a box of big contractor bags with me. Bag it and seal it.

gennady

why

You post is unclear to me.

Pressure is a pressure. You can express it in head (feet or inches etc) or force per unit of surface.

Pressure difference at the beginning and end of the pipe is what moving water trough the pipe.

Pressure loss (or head loss etc)in a piping system is a loss of pressure of the water moving trough the pipe.



Pressure loss is a function of square of water velocity, length of the pipe and diameter of the pipe.



In a closed heating system pressure difference is created by circulator. Each circulator has a pressure/flow curve, describing its pumping (circulating) capacity. Each piping system has its own pressure/flow curve as well, The point where these 2 curves intersect is the point where pressure(head) and flow of the pump is same as pressure drop and flow of the system. Circulator adequate for system must have head/flow curve intersect with system curve in a point, providing sufficient flow to deliver heat to the radiator.

If circulator head/flow chart intersects with system pressure loss/flow with flow less then needed, then high delta T will be present.



Regarding Gravity self circulating system , moving force of the water is prssire differencial due to density difference of hot and cold water in supply and return.



Correct me if I'm wrong.

I'm eager to learn

icesailor

Go/No Go Flow:

Gordy,

The house was built in the early '70's.

The boiler was replaced in 2005.

I doubt that it had a boiler by-pass in 1970.

The boiler was old when it was replaced. I'm old too.

It must have worked from 1970 to 2005.

It must have worked for the parents from 2005 to the present when Eric took it over. The problem started when someone started over thinking the problems. He noticed that the heat didn't come out of the baseboards that well. He vacuumed out the fin tubes.  The heat started coming out of the elements better.

There is no mention of any "improvements" to the structure. I have never seen a structure with a split series loop with balancing valves that didn't work and balance out equally.

The only time I ever saw something like what he described is when some hot shot series piped a K-41 Beacon Morris fan coil into the 3/4" loop. It put so much restriction on the loop that it wouldn't get hot past the K41. One pipe it with a mono-flow and the problem is solved. And it was pumped with a 007. Actually, I think that two K-41's were piped in.

The only way I have ever seen circuit setters on a residential job like that is wide open. Over time, the whole zone gets hot.

Zman

Remove the circ...

I think you need to remove and inspect the circulator. It is the most likely culprit of your problem.

The 007 is likely the correct size. I do not believe you can size circulators accurately by first guessing at the length of pipe then guessing at the head/ft per 100. The 6 per 100 number is based on pipes at max flow. The 1" in this scenario will see 5 gpm the 3/4" won't see more than 3 gpm. Sure a 0012 will heat the house and you won't get a call back. It will be oversized.

If you replace with a 3 speed circ you can adjust the speed to get the desired delta T.

You could always take ME's offer to accurately size your circulator. With that you would be guaranteed success.

I mean no disrespect to the folks helping on this one.

This post has veered way of course.

Carl

Earl

Balance Valve

Here's a pic of what I'm calling a balance valve, a screw driver ball valve to me. There's one at the end of each of the loops.





Earl

Earl

it veered and hit 6 houses and 2 walmarts before rolling

I agree, the thread has veered way off and that doesn't help.





Earl

Earl

Odd tee

Here's a pic of the odd looking tee. Don't know if it's just a tee or a special one. It takes the 1" off the boiler down to the two 3/4" loops. It's on the supply side.



Earl

SWEI

looks like a reducing tee to me

1 x 3/4 x 3/4

Earl

New info

New info to report. I closed down the 58' loop and opened the balancing valve up fully on the 42' loop and the delta T came up under 20. I tried this same test with the 58' loop but the balance valve won't shut off the flow completely on the 42' loop so I wasn't able to test the 58' loop. I plan to add a ball valve to the 42' loop so I can closed it off to test the 58' loop for delta T.



That tells me the 42' loop is fine and that the circ is ok for at least that GPM/Head. I'm thinking maybe I have a issue on the 58' loop or the circ. I haven't had a chance to measure piping and count the fittings yet to size the circ.



Is there a way to check for any blockage in the 58' loop?



Earl 

icesailor

Ball Valve:

That is not a ball valve. At best, it is a diverter valve. The slot for the screwdriver shows the direction of the blade inside. It is showing that the valve is about 1/2 closed. A ball valve will give you a 100% positive shut off. That valve will not.

Those were popular with suppliers to be included with heating jobs to make people think that they were doing something cool.  What was cool about the ones I saw was that you could usually turn one but not the other, and one usually leaked. I never touched them for adjustments. Those old bomb proof, over-piped heating systems (by today;s standards) never needed no stinkin adjustments. They were more like that EverReady Bunny, Could take a licking and keep on ticking.

Earl

Circ Spec

Sweet, I will measure and count the fittings when I get the chance. I take you want the tube/fin measured by the amount of tube/fin and not the lenght of the housings, correct?



Yes, I do know cast boilers have a limit on how low of a temp you can have on the return. I just don't know my boilers spec cause Burnham doesn't say, only that I had to put the bypass in to protect the boiler. As far as I can tell, most cast boilers require 140 plus so that's what spec I use. Burnham tells you to install the bypass and how to use it and why, but doesn't bother to tell you what the specs are. Worthless!



Earl

Earl

Explains it

Yes, I found out it doesn't shut off the flow complelely like you stated. I didn't think they'd be a buttery fly valve, I figured ball valve. They do rotate 360 degs, there are no stops, explains why they don't seal 100%.



Thanks,

Earl

SWEI

balancing valves

I avoid them like the plague.



Proper hydraulic design works so much better...

Earl

Tee

I thought so too, but wasn't sure if it was anything special, like to divert flow or such.



Thanks,

Earl

icesailor

Obsessions:

The whole thing is fine. There's no blockage in the 54' circuit.  You have an obsession with Delta T's and GPM's.

If you insist on futzing with it, replace those "things" with a couple of zone valves and have two thermostats. You will split the house into two zones and it won't matter much about which circcuit gets the flow. The house will be more evenly heated and your problems will be solved.

A couple of Taco ESP's would be nice.

Paul48

42' loop

21000 btus divided by 15* DT=1400 divided by 500= 2.8 GPM

Looking at the curve for the 007.....2.8 is about 9.6 ft head and that circ tops out at about 9.8 ft.

You either have a problem with the impeller of that circ, or it is not the right size for the system.I think the 58' loop is pushing the limits with the 007, and that's why you can't get adequate flow. Can you give the details of the longest loop?

Earl

Rolling my eyes

Tell me this, why don't I have correct even heat if it's all in my obession?? You are no help at all. Thanks anyways! If I wanted to add zone valves and spend a lot of money, I'd hire a bad contractor.



Earl

Earl

58' Loop

I'm hoping to measure the loops and such this weekend. I will post my measurements and what I come up with circ size using the Taco's circ sizing guide.



Thanks,

Earl

icesailor

Obsessions:

Rest assured that there may be over 1,000,000 hot water boilers piped exactly like yours. They all work fine and no one ever tried to check if the circuits had a 20 degree Delta T  along with the correct flow rates. Years ago, I did that. On a scale of 1 though ten, it amounted to a minus 1 (-1). It is only really useful in very large commercial, high emitting applications. Or the system is under sized and needs to be over pumped. You are trying to create perfection. You won't. But you can try. Knock yourself out.

What you are trying to do gets averaged out. In the scheme of things, you have "great big pipes" compared to the fine spaghetti of today. A pound of macaroni fits in a much larger box than fits in a box of spaghetti. If you have a 3/4" loop, and you need a great big pump to overcome the resistance of the circuit, you will have a great big noisy pump. And you might get that elusive Delta T you are looking for. Because the water will be so much cooler because it had to give up "X" amount of heat in its trip around the zone. But, 1" pipe is probably too big, the flow will speed will go down but the GPM's will go up, because the pump sees less resistance. So, if you pump it into a 1" main, split it, and bring it back together again, it works better.

Chase the elusive Delta T. Good luck finding it. But you are nonsensical. You are willing to buy a big new pump and the related equipment and labor to install it, but not install zone valves, which will solve problems that the new pump may not. You have to think like water to understand where it goes and how it gets there.

I'm only bothering to write all this because no one has told me that my scenario is wrong, and maybe someone else will understand what I am saying and it will be helpful. Back in the Pleistocene era, there were no Internet Forums like Heating Help.Com where we/I could go to get information. If you asked someone, they probably didn't know the answer and got PO'ed for someone to ask them something that they should know.

I'm trying to resolve some steam issues for a customer. I've been pretty successful. Try using Delta T on a steam system.

Eighty "O's".  

NRT_Rob

um

ok, the system worked and then it didn't. the problem is not circ sizing.



basic sanity should also confirm this. while you might not hit a magic 20 degree Dt, this circ is VERY capable of delivering better than 60 degree DT. you have a flow problem. it is not related to circulator SIZING. you could not possibly have an undersized circulator to the point of a 60 degree DT.



you either have a bad circ, bad balancing strategy, clogged valving, or some other flow restriction/balancing problem.



you most definitely do not have an undersized circ to any degree that you should be concerned with.

Paul48

You're Right

It points to bad circulation.It worked before.

Zman

15-58

It will take 4 bolts and 3 wires. Swap your circ for a grundfos 15-58. Open up all "balancing" valves and watch it go. You will have 3 speeds to play with and your delta T will be exactly what you want If you want to get real crazy put in a delta t circ.

Nice work with the 2 Walmarts. Hope they were superstores.

Carl

Ironman

Common Sense: The Missing Diagnostic Tool

I have to agree and re-iterate that your problem is not an under-sized circ. If it worked before with a 007, then the size of the circ is not the issue.



More than one of us has offered you the simplest and easiest first step: closing off the bypass. Did you try that? If so, what were the results?



If you still had issues after that, then look a the impeller of the circ.



I couldn't count the number of houses that I've seen that have much more piping than yours and a 007 carry's them fine. It's not unusual to see 5 + zones and hundreds of feet of piping running and working on a 007. As Rob said, it may not be a perfect design, but it works.



Look for the simple, common sense solution.

Earl

Never said it worked before

Never said the system worked before. I have no idea if it did or didn't. I just know it doesn't now. The circ came with the boiler and it was never sized to the system. When I lived in this house I was just a kid. In 2005 I installed the boiler for my parents and all I know is the boiler put out heat and the pipiing all got hot. They never complained but I don't know if they didn't noticed or if it didn't work correctly than. I have no idea what circ was on the old boiler. Sizing the circ seems like a cheap and easy way to make sure the circ size isn't my problem.



As I stated before, the bypass was closed until I reduced flow to the 42' loop to get more heat out of the 58' loop. Than my return temp dropped to 120 to the boiler, not good, so I opened the bypass to keep the return temp to 140. If I open the 42' loop up I have great heat on the 42' loop, none on the 58' loop and the boiler return is about 160.



Earl

Earl

Never said it worked before

I never said it worked before. I don't know if it did or didn't. I know currently it doesn't.



Earl

NRT_Rob

it seems doubtful

that someone ran the system for seven years with a non-heating loop?



regardless, even if it never did, the choice of a 007 is definitely not your problem and you can definitely heat this house with that pump, if it can be heated with this radiation in this piping configuration. as long as the pump isn't bad, of course.

Earl

Never said it worked before

I never said it worked before, I have no idea if it worked before or not. The circ came with the boiler and was never sized. I installed the boiler. DId the boiler get hot, yes, did it pump hot water through the piping, yes. Did it do it correctly and equal, no idea. Parents never complained, did it work correctly or didn't they noticed or is it a new issue? No clue.



Earl

Earl

Don't like the zone valve

Zone valves just wouldn't help. Both t-stats would always call at the same time and I'd still have the same prob.



Ok, say I threw the delta T out the window. How do I troubleshoot the system? I'm only using delta T cause that's all I have to work with and how systems are built. Now I can't use any metering as I don't have access to trade tooling. I started out using my hand and I could feel the two loops weren't balanced. So then I dug out my trusty laser and contact thermomters. I'd hire a contractor but I don't have the cash and trying to find good contractors anymore isn't easy.



Earl

NRT_Rob

.

-purge the long loop and make sure flow through the entire circuit works smoothly and cleanly.



-close the bypass, and see if return temp stabilizes once the rooms heat up. seems unlikely you'd need a bypass here in the end, you probably aren't going to have a 40 degree dt in stable operation.



I wonder if you have a "bullhead" return where both circuits face each other where they reconnect on the return. if so you might be checking flow in one loop with flow in the other. that's a small piping change.