High delta T, how to adjust it?

Earl

I have a split loop baseboard system. It has 42.5' of slant/fin baseboard on one loop and 58' on the other. Both loops are 3/4" split off 1" from the boiler and return on a 1". The circ is a Taco 007. Both loops have a manual ball valve balance valve on the return before they merge into the 1" return.  

House would take many hours to heat up. I cleaned out all the baseboard heaters and man, I had heat like crazy on the 42.5' loop but hardly nothing out of the 58' loop. So I checked the balance valves and found both were fully open. So I adjusted the 42.5' loop down until both loops had the same return heat (balanced them by temp readings). That helped the 58' loop a lot but it still doesn't put out what it should. Also when I did that, the 42.5' loop has reduced heat output. I'm getting 120 return on each loop (after i balanced them) with 180 supply. No where near the standard 20 delta T. I had to open the bypass to get the boiler return temp up to 140 to protect the boiler.

I believe to raise the return temp/lower the delta T, you need to push more GPM, correct? To lower return temp, less GPM, correct? So how do I balance these two loops and get a decent delta T across the loops? Is my circ not up to the job to provide enough GPM across both loops? 

Thanks!

Ironman

Delta T

The 007 should be sufficient.



A baseboard system with that small amount of fin tube should not need a bypass. Close it down and see what happens.

Earl

Delta T

Bypass was closed prior to balancing out the loops. I had to open bypass cause my return temp was down to 120 to the boiler afterwards. Bypass was always closed before that. I should of took readings before balancing the loops. I may open the one balancing valve that I adjusted and close the bypass and see what return temps are with the system the way it was before I messed with it.



Earl 

Zman

how much...

How much piping is there in the loop?

What size is the boiler?

Are there other zones?

Carl

gennady

circulator

you need 0012 taco circulator. 58'+42'=100' at 500btu per foot you get 50,000 btu output total. at 20F delra T your GPM is 50000/10000=5GPM your head around 58*3*0.06=10.5'

looking at taco chart you see 0012

http://www.taco-hvac.com/uploads/FileLibrary/101-035.pdf

you have to install circuit setters thou to set flows

Zman

How in the world...

Gennedy,

How do you figure head loss with no piping lengths? You lost me!

Carl

Zman

3

The 3 is SWAG, yes?

Carl

gennady

head

just assumed lenght of baseboard as a part of supply, then same goes for return pipe and some for risers. of cause it is very approximate, but better then nothing. 008 taco will work too. Also for head assumption dimeznsions of the house can be used as (W+L+H)X2 .

Mark Eatherton

Go with the flow....

It almost sounds as if it struggles coming out of a deep set back, no? If so, not all systems are conducive to deep set back and fast recovery.



It is best to run the (hydraulic) numbers. This way, you get exactly what you need without wasting time and parts.



But your problem is the reverse of what post peoples problem is. Most people want to INCREASE their delta T. And you are headed in the right direction. Increasing flow decreases delta T. So does shedding load. If in fact this is a scenario where the system is coming out of a deep setback, you need to assess it under NORMAL operating condition,s and then you might find that the DT is just fine.



Good of you to recognize the fact that an long term entering water temp below 140 is not good for your appliance. Now, were it a modcon, you;d be singing a different tune...



Balancing is supposed to be done based on connected loads, and not necessairily trying to achieve the same thermal balance, especially if the loops are significantly different in loads, as yours are. If the loops were of equal load and length, then the return temps would be the same.



If you can give me the EXACT lengths of BBR, pipes, fittings, etc, I can run the calculation through Siegenthaler's software and see what it says as it pertains to pump sizing.



ME

RJ_4

Installers

Ball valves should be used for on off oper. For balancing,  circut setters or globe style control valves are better. Than you can set up a flow meter and read flow rates.

Earl

Boiler and piping info

Boiler:

Burnham PV83WC with the high flow nozzle

DOE-123 MBH with high flow nozzle

IBR-107 MBH with high flow nozzle

Piping:

Unknow, I will measure pipng. I do have a copy of Taco's circ sizing PDF.

Loop:

Split loop (2 zones, east and west) no zone valves, single t-stat



Earl

Earl

valves

The balance valves were installed when the system/house was built in the early 70's. They are ball valves that you adjust with a flat blade screwdriver. I'm guessing standard stuff back in the day.

I'm a home owner, I have no flow meter or other tools of the trade. Only a contact and noncontact thermometer to work with.

Earl

Earl

Deep setback

No deep setback, I keep the t-stat at the same setting 24/7. It's a 2 deg span t-stat.

I balanced the loops by temp since I have no trade tooling. I can't read flow, only temps.

EricAune

Agree with Mark

The first hing that raises my brow is the idea you are trying to recover from a deep set back at the thermostat.  Is this the case?  Mark hit it right on the head for me.



Also, balancing is never achieved properly or repeatedly with ball valves.  Your method of balancing via similar return temps doesn't reflect the proper flow needed in one loop or the other.  The longer loop should have a higher load, therefor requiring a higher flow.  It may be miniscule in it's difference but, nonetheless they are not going to be the same.



Given the numbers you've stated, barring any major fitting-racetrack type of piping arrangements, you should be in business with a 007.

Earl

No deep setback

No deep setback, t-stat stays at same setting 24/7 and is a 2 deg span. The many hours slow recovery was fixed when I cleaned out the heaters. I'm just not getting nornal level of heat that I should and very high delta T numbers. 60 instead of near 20.



Ball valves (adjusted by screwdriver) is what was installed in the early 70's when the house was built, that's what I have to work with. I have no flow meter. My method may no be correct, but it sure did help the 58' loop. If I open the 42.5' loop up, it generates heat big time and the 58' loop barely warm to the touch.

Tonight after work, I will open the 42.5' loop back up (were it was before I messed with it) and retake temp readings.



Earl

EricAune

Question

I'm sorry, I interpreted your description of the valves to be something else [like a lever handle ball valve]



One question, can you post pictures of how the supply and return piping is configured near the boiler?  I'm wondering if there isn't a "bullheaded tee", likely on the return side, that is causing this. This would be a case where the returns from each loop enter a tee fitting from each end, then the flow back to the boiler is through the side port of that same tee.



Just an idea.

Earl

Ball valves without handles

There's a sweat tee at the suppy to both loops, not your standard looking tee. I will take a pic of it. Been there since the system installed in early 70's. The only mod done is a new boiler installed in fall of 2005 and the at boiler piping kept the same other than I added the bypass as per Burnham. Boiler was rated the same as the old boiler. Yes I know, it's probably way oversized, but I didn't know any better back than.



The loops return on a 1" copper. They are "Y" into the 1" with a sweat "Y".



I will also take pics of the balance valves, which to me are ball valves without handles.



Earl

NRT_Rob

inadequate heat

and high delta T USUALLY says to me flow problem. even if your current pump is undersized this delta-T is extreme.



I would guess air problem. most especially if the system has been opened for any reason recently. would be solved by a good purging in most cases.

Earl

air

No air in the system. Has an air scoop and auto vent, always left open. No noises. System hasn't been drained/opened since 2005. No leaks either. Im still leaning towards not enough GPM. I need to calculate my head and GPM and see if my circ is sized correctly. It came with the prepack boiler.



Can a circ wear out, loosing GPM but sill pump some GPM?





Earl

NRT_Rob

maybe

but with a 60 degree DT, you'd be pushing 30,000 BTUs per GPM. so with your boiler as the high limit on output, you'd be stuck at about 4 GPM max or you're breaking the laws of physics.



but it's worse. with a 150 average temp in your baseboard, you're down to 380 BTU/ft. or 38,000 BTUs, or about 1.2 GPM max. whatever your pump can or can't do here, it can certainly pump more than 1.2 GPM through 2 circuits of baseboard.



unless it's clogged. or broken. valve it off, pull it out, and try a hose and bucket flow test maybe. if you're pumping toward the boiler, might be able to experiment with short dead head and the pressure gauge to see how hard it's pushing..

Zman

Check the circ

I bet the circ is plugged up or not working at all. You could be gravity feeding 60 delta T. A 007 does not sound that far off for your installation.

Carl

icesailor

I've seen:

I've seen a lot of chips in my time, but I've never seen a heating system like described that at some point, regardless of what the  high limit was set at, the system settled out somewhere. With a boiler rated at 113,000 IBR, that would have to be one big hacienda to not be working, and that's since way back (when the house was built)? And this problem just showed up?

A little knowledge can go the wrong way. The last time I saw something like this and it came out of the boiler very hot but came back cool, something got into the pump volute and stripped a large amount of the vanes off the impeller. Hence, very low flow.

I've seen it far more often on 006 Bronze circulators where the water breaks them down.

A 008 or a 012 would solve the problem. The 007 that is there will too.

When in doubt, replace the circulator. And don't use one of those (*&^%$#%^* red rubber gaskets that will leak. Use the black square cut O-rings that come in the box

Earl

Thanks for the info

Thanks for the info everybody! First I will use Taco's paperwork for specing a circ and see if the 007 is in range or not. Once I confirm the correct cric I will look at the circ itself.



The circ does run, I can hear it and the pipes get hot when it runs. There's a flow check so if it didn't operate, it couldn't gravity feed unless I used the manual thumb screw, which I'm sure is frozen.



I will take and post pics of the balance valves and the odd tee. I will also take pics of the at boiler piping.



BTW, I looked at the 42.5' loop balancing valve setting and it's about 3/4 closed and the 58' loop is fully open. So thats how much I changed the flow to the 42.5' loop to get decent flow to the 58' loop and they are balanced by return temp since thats the only method I have to balance them. Before I started, both balancing valves were fully open.



Earl

Greig1

Amp draw on pump

I can not belive that nobody has asked him to check the amp draw on the pump to see if it is even pumping. So I will check your amp draw on the pump, look under the cover on the Taco pump to get it's full load amp draw. Is it in it's working parameters. If not replace it. Did the system work well before? If it did I would really suspect the pump. A high amp draw is a bad bearing, bad windings or the scoop of the impellear is worn out. Replace the pump!

Earl

amp draw

I do have an amp clamp. I will check it's draw. It's my parents house. I just took it over and the heating system sucks! I installed the boiler for them back in 2005 and they never complained about it. I know the baseboard heaters we never cleaned and when I cleaned them that made such a huge improvement. The curtains started to wave from the heat when nothing before. In the low 30's high 20's the circ would run all night and never met temp till I cleaned the baseboards. Well, had very very little heat on the 58' loop even after cleaning. So that's when I checked the balance valves and found them both fully open, which isn't right seeing as the loops aren't equal. So that's when I checked the temps and closed off the good loop to bring more heat out of the bad loop. It worked, but I lost the great heat on the 42' loop. It still puts heat out, just not like it did before I balanced the return temps. Ended up with 42' loop 3/4 closed and the 58' loop fully open. I still think I have a low GPM, under sized pump, bad pump, etc. If the short loop is closed off 3/4 of the way to get more GPM to the other loop, seems like low GPM. But I will check amp draw on the circ and will follow Taco's guidelines for checking head and such to see if my circ is the correct circ.



Earl

gennady

SWAG

SWAGuess.

Actually not.

First your comment made me upset, But then, I think to myself, when i start a new project and I do complete project modeling on my computer, and then i build it, and it works exactly as i designed it , I feel happy. Today i spent hours figuring out why Paxton controller did not work as i designed with 2 Grundfos VFD Magna and one Belimo 0-10 vdc actuator, and i found out , that control wire, running next to 24v power feed gave me 0.85vdc offset, and i corrected this problem and everything fell into the picture and i had perfectly functioning system. It made me happy. So your comment did not upset me.

Earl

amp draw checked

I checked the amp draw. Cover says .71 and I got .66 and if I open the bypass (less load) the amp draw went to .73

icesailor

Huh?

You are over thinking this.

From what you describe, consider this. If the house is 28'X48' , and the boiler is in the middle of the house at one end, the 1" main could be 42' +/- from the boiler to the far end where it splits.  Each side loop has two short sides (12.+12') or 24' and the long side. 44'. Or 68' per side. Times 2. That falls well within your measurements. There has never been a 007 that wouldn't push water through that. 007's were designed for that.

My home that I live in, has 5 zones on two floors. I have baseboard zones on two floors, all zone valves at the boiler and all zones are home runs. I have no idea how much 3/4" copper tube are installed but there is well over 400'. It ran fine with a 007 circulator. I changed it to a Wilo Stratos ECM circulator a few years ago.

Absolutely everything you have posted screams something wrong with the circulator.

In 1957, it has a Series 100. It failed and a 007 was substituted. It worked fine for years. You cleaned the fuzzies from the elements and the curtains did the heat dance. It was working then. What changed?

If you awitch it to  Taco high head 012 or a 008, and it works, you will think it was solved by the new high flow circulator. I'll bet that if you changed it to a three speed, and it works, you could run it on low speed and heat the house.

gennady

head

if it is 1 story house according your assumed measurements head will be (10+28+48)x2X0.06=10.32'

there is no 007 taco that will go over 10' of head.

Mark Eatherton

More amps =

More work, more work should = more GPMs. More GPMs should = lower delta T.



Sounds like the circuit could be air bound.



Have you tried force purging yet? If no, try it with pumps off. Do one circuit at a time.



ME

Mark Eatherton

Probably not a ball..

Probably a blade or butterfly type of valve which has to be turned to 3/4 closed before it even begins influencing flow. The only device that had a straight screw driver slot with a ball was the crappy isolation flanges Grundfos use to use on their pumps, and they leaked like a sieve if you used them...



ME

gennady

amps

let's say i try to use this 007 taco for pumping water into tank located 125' up on the roof. this pump will lift water to max head, and then all energy consumed by pump will go into heating water around the pump, but no water will be moved. amps will be to the max, but the water will not be moved.

Mark Eatherton

I disagree Gennady...

Next time you find a small circulator with Gage's on both sides of the circ, look at the amp draw with the valves open(assuming it IS already moving fluid), then close the outlet valve and see what the amps do. They should drop because the pump is not moving any fluid,, doing any constructive work. Oh sure, it's generation maximum delta P, but it's not moving fluid, so it's really NOT working hard...



ME

icesailor

Blade Flow Controls:

Me,

Flair made those or something like them. There was a Wholesaler around years ago that always had the latest cheap stuff to keep the job cost down. He supplied them like candy. Like you said, they always leaked after you turned the screw. I think they were made in Eastern Europe.

Real junk though. I see them all the time. Guys think they are positive shut offs but they aren't.

gennady

amps

you are right, amps in this case will not be max, only to support weight of water column.

icesailor

Huh?

Gennady,

You (and others) are confusing the ability of a hydronic heating pump to "pump" water in a closed loop system to a higher place and not factoring in the Ferris Wheel Effect of the water coming down the other side to counteract the rise. Pressure/Altitude Head has absolutely no effect on a multi-floor heating system. As long as the pressure in the system is high enough to support the column of water to the upper floor with enough left over to keep pressure, the only function of "head" is to overcome piping resistance.

I've put gauges on zones to see what happens. I've done it for chips and giggles. The only rise over the static pressure is when the circulator starts. The head is the difference on either side of the circulator. The outlet is higher, the inlet is lower. The differential is the "head". The "Head" differential is supposed to be how many GPM's that particular circulator is moving.

Supposedly.

gennady

head

Hydrolic resistance of the system, AKA friction loss, dictates how many GPM is circulated trough closed loop. dependency of flow from system resistance is reflected in pump curve. higher resistance leads to lower GPM. picking up pump is a process of comparing system characteristics to pump characteristics. that's all. there is a limit to how many GPM each particular pump can push trough particular system system.

Zman

No offense

Gennedy,

I meant know offense by the Swag comment. I was using the acronym to mean Scientific wild **** guess. Given the information provided, I don't think it is a bad way to ballpark. I was familiar the .06 multiplier, I just had never seen the 3 before. I understand your logic.

Carl

Mark Eatherton

Probably one in the same Chris....

I think the ones I remember we're called Thrift balance valves. They still make and sell them. Better than nothing in my opinion but if properly designed, other than initial purging, are not necessary. Mo flo is mo beta:-)



ME

Earl

amp draw

I forgot to mention when I dead headed the circ, the amp draw stayed at .67, shouldn't it of maxed out on amps? If I closed the suppy, it stayed the same, if I closed the discharge, it stayed the same. The only time the amp load changed was when I opened the bypass fully which is right by the circ the amp draw went up to .73. I'm not up on motors but I would think the harder the motor works, the higher the amp draw, circ seems to be backwards of that. Also I noticed the motor on the circ is very hot, 170 degs.



Earl

Earl

Curtains dancing

What changed? I adjusted the balance valve on the 42' loop to get more heat out of the 58' loop. That caused more heat out of the 58' loop and reduced the 42' loop. They both heat equally now but both at reduced heat output. That's my problem. Low heat and very high delta T's, all which tells me I'm low on GPM, just need to confirm that before buying parts and/or wasting time changing out parts.



Earl