Overpumping emitters.

Paul48

@SWEI .......Can you elaborate on that, a bit?

Steamhead

Hatterasguy said:

Steamhead said:

Question for the ΔT circ guys: As I understand it, this type of circ will slow down to increase the system's ΔT. However, since a converted gravity system won't circulate well with a too-low flow rate, it seems possible that a ΔT circ might slow down past this point until the boiler warms up enough to speed up the circ. This would make the system heat unevenly. Thoughts?

I've disagreed with your pumping philosophy on converted gravity from the outset.

Using a giant pump to ensure high velocities so all rads get instant heat is counterproductive to efficiency.

A ΔT circ will start at maximum speed on these systems during a cold start as the ΔT is massive (50F or more). So, you won't have any issues at that time.

Once the ΔT narrows to setpoint, the circulator is going to slow to maintain that ΔT. It's exactly what you desire on a CI system. Of course you'd need boiler protection as the flow rate on startup is huge and the boiler cannot possibly keep up (same as what you currently have with the giant pump).

The flow rate at equilibrium will probably be significantly less than your current systems, thereby requiring you to use balancing valves to create head in the rads closest to the boiler. These valves take time and patience to adjust, especially if there are no flow rate indicators. But, at the end of the day, you'd have a far more efficient system.

You have it backwards. Read the two articles and threads again. In all of these, the object was to eliminate over-pumping which was causing water to short-circuit thru the radiators, thereby reducing their efficiency.

SWEI

We have installed mod/con boilers in several gravity retrofits using much smaller pumps running constant circulation and ODR.

e.g. 132k design day heat loss, 154k DOE boiler, VR1816F set to the lowest constant pressure setting (~5 feet.) Result? Near-perfect (± 1.5°F) indoor temp control last season with NO thermostat and NO modulation of the zone valves (controls were not installed until this summer.) Three 3" mains, 250+ gallons of water, and the weirdest piping we'd ever seen. It just works. Once you eliminate both on/off pumping and on/off firing, these systems can be minimally pumped which comes closer to emulating their original operation with gravity circulation.

If we had used that same pump on a single stage boiler with an on/off thermostat, I believe we would only have had heat in about 60% of the radiators.

Paul48

I don't see the need to jump to a higher velocity circ. The problem might exist, even if you were running "gravity". The system needs to be balanced.

Gordy

Built in buffering helps. 250 plus gallons of system water content performs just like a buffer tank. Along with the mass of all the iron of the rads, and piping.

I think it is fair to say when it comes to low mass base board emitters. It creates issues back at the boiler. Mod/con, or CI. With standing iron, or radiant not so much.

SWEI

Higher velocity in this case would have meant something like a Series 100, which would have pushed somewhere around 25 GPM through this system. We're moving about half that with all zone valves open 100%.

hot_rod

SWEI said:

Higher velocity in this case would have meant something like a Series 100, which would have pushed somewhere around 25 GPM through this system. We're moving about half that with all zone valves open 100%.

hot_rod

hot rod said:

SWEI said:

Higher velocity in this case would have meant something like a Series 100, which would have pushed somewhere around 25 GPM through this system. We're moving about half that with all zone valves open 100%.

When you say a much smaller pump, you need to move that132k load at design conditions. Why would it ever require a 25 Gpm pump?

Gordy

I believe that was Kurts point. The benefits of constant circulation with a smaller pump is as you describe Hat.

However his point is with a bang set up he would need a larger pump to make up for the imbalances that type of control could, or would create. A system control that runs on the edge of the heat loss as constant as possible is hands down the best type achievable.

The system he describes has huge amounts of mass. Cold soak then bang hot making set point then cold soak needs more pump to get the mass mixed. With constant circulation it's always mixed there fore one can get by with a smaller circ.

Steamhead

Hatterasguy said:

Steamhead said:

Hatterasguy said:

Steamhead said:

Question for the ΔT circ guys: As I understand it, this type of circ will slow down to increase the system's ΔT. However, since a converted gravity system won't circulate well with a too-low flow rate, it seems possible that a ΔT circ might slow down past this point until the boiler warms up enough to speed up the circ. This would make the system heat unevenly. Thoughts?

I've disagreed with your pumping philosophy on converted gravity from the outset.

Using a giant pump to ensure high velocities so all rads get instant heat is counterproductive to efficiency.

A ΔT circ will start at maximum speed on these systems during a cold start as the ΔT is massive (50F or more). So, you won't have any issues at that time.

Once the ΔT narrows to setpoint, the circulator is going to slow to maintain that ΔT. It's exactly what you desire on a CI system. Of course you'd need boiler protection as the flow rate on startup is huge and the boiler cannot possibly keep up (same as what you currently have with the giant pump).

The flow rate at equilibrium will probably be significantly less than your current systems, thereby requiring you to use balancing valves to create head in the rads closest to the boiler. These valves take time and patience to adjust, especially if there are no flow rate indicators. But, at the end of the day, you'd have a far more efficient system.

You have it backwards. Read the two articles and threads again. In all of these, the object was to eliminate over-pumping which was causing water to short-circuit thru the radiators, thereby reducing their efficiency.

This article was the basis for the argument:

https://heatinghelp.com/systems-help-center/sizing-circulators-for-old-gravity-hot-water-heating-systems/

The other articles are contrary to this article and prove that you can easily overpump a CI system with the giant pumps referenced in this article.

You need to read it again. Here is the first paragraph:

"When servicing old hot-water heating systems that originally circulated by gravity, but now use circulating pumps, I began to notice a lot of oversized circulators. In some cases, the circulator was so severely oversized that the boiler could hardly get any heat out to the radiators. The water couldn't pick up much heat in the boiler or shed it in the radiators because it was moving so fast. There is very little resistance in the large pipes of a gravity system, so the consequences of oversizing the circulator are more severe than in a newer system with smaller pipes."

How is this advocating oversized circs?

Steamhead

Actually, you do. You certainly missed this part:

"If a heat-loss calculation indicates using a smaller boiler than the amount of radiation would seem to indicate, size the circulator (but not the boiler) to the radiation. Again, even though you're not generating as much heat, the radiators and pipes are still there with all that water in them."

The object, as stated earlier, is to make sure you have enough circulation that the water will circulate to all the radiators. You don't need more than that, but any less will result in call-backs from uneven heat. Call-backs are bad because we generally don't get paid for them.

I tried this method on a bunch of systems, including my own, before writing the article. It worked every time. Can you say the same?

Gordy

Steamhead said:

Hatterasguy said:

Steamhead said:

Hatterasguy said:

Steamhead said:

Question for the ΔT circ guys: As I understand it, this type of circ will slow down to increase the system's ΔT. However, since a converted gravity system won't circulate well with a too-low flow rate, it seems possible that a ΔT circ might slow down past this point until the boiler warms up enough to speed up the circ. This would make the system heat unevenly. Thoughts?

I've disagreed with your pumping philosophy on converted gravity from the outset.

Using a giant pump to ensure high velocities so all rads get instant heat is counterproductive to efficiency.

A ΔT circ will start at maximum speed on these systems during a cold start as the ΔT is massive (50F or more). So, you won't have any issues at that time.

Once the ΔT narrows to setpoint, the circulator is going to slow to maintain that ΔT. It's exactly what you desire on a CI system. Of course you'd need boiler protection as the flow rate on startup is huge and the boiler cannot possibly keep up (same as what you currently have with the giant pump).

The flow rate at equilibrium will probably be significantly less than your current systems, thereby requiring you to use balancing valves to create head in the rads closest to the boiler. These valves take time and patience to adjust, especially if there are no flow rate indicators. But, at the end of the day, you'd have a far more efficient system.

You have it backwards. Read the two articles and threads again. In all of these, the object was to eliminate over-pumping which was causing water to short-circuit thru the radiators, thereby reducing their efficiency.

This article was the basis for the argument:

https://heatinghelp.com/systems-help-center/sizing-circulators-for-old-gravity-hot-water-heating-systems/

The other articles are contrary to this article and prove that you can easily overpump a CI system with the giant pumps referenced in this article.

You need to read it again. Here is the first paragraph:

"When servicing old hot-water heating systems that originally circulated by gravity, but now use circulating pumps, I began to notice a lot of oversized circulators. In some cases, the circulator was so severely oversized that the boiler could hardly get any heat out to the radiators. The water couldn't pick up much heat in the boiler or shed it in the radiators because it was moving so fast. There is very little resistance in the large pipes of a gravity system, so the consequences of oversizing the circulator are more severe than in a newer system with smaller pipes."

How is this advocating oversized circs?

Now we are drifting back to Harvey's original question. Okay Harvey come back

Paul48

The chart instructs that a gravity conversion should be pumped at 1/3 more gpm than a modern system. I believe Hat is saying this is not necessary, if you just balance the system.

Steamhead

I've only run into a couple that had balancing problems. These were due to valves that were not fully open. In one case, we had to replace a couple of valves because they were hopelessly stuck.

If you read the old B&G handbooks, you will see where the extra volume came from. The Dead Men who wrote them were giving us the benefit of their experience. They found that a circ sized for a newer system just did not move enough water to properly circulate all the water in old gravity piping. I verified this in my own system- when I tried a B&G NRF-9F/LW, the rads at the ends of the mains did not heat well. The Grundfos UP15-42F was just enough to circulate those rads, so that's what I ended up with. My results agreed with theirs.

Hatterasguy, I'll repeat my question. How many of these systems have you worked on? I think I know the answer, but I'll wait for you to tell us.

Gordy

I do believe that Frank's article was written before the onset of DT circs, and DP circs became common place in the industry.

As for balancing, and getting by with a smaller circ. I think one needs to be aware that spending possibly several visits to the site is costly. Obviously the owner would have to absorb these costs since the contractor would go broke with complimentary system balancing. That would be if all valves operated correctly.

I really think that for the time the article was written that the observations, and remedies were the cheapest most effective solutions for both the owner, and the contractor.

Steamhead

It was. But I included the method for selecting other circs than were shown in the article. In that respect, it's future-proofed.

I can only think of one customer who wanted to tweak-out his circs. Everyone else wanted it fixed in one trip. Again, I've never had an issue with my method. Given what I've found in the field, in every case the customer was much better off.

Steamhead

Hatterasguy said:

Do you know how many licensed contractors in NYC use giant pumps on HW and have a DT in the weeds and make the same comment.........."I've been doing this for 30 years and never had a problem?"

The sad part about this business is that THEY are the problem.

Let's just agree to disagree that "the customer was much better off".

They obviously never saw my article!

But let's get into some specifics. How much radiation, in EDR, was on these systems? What size pumps did they use?

Gordy

I would like to know the gravity system flow rates under gravity flow. I will be willing to bet they were higher than we suspect. Especially with more elevation.

Keep in mind the envelope of the period. The temp swings that were probably endured. I highly doubt one held +/- 1 degree on room setpoint. So the system water content was probably pretty cold when you lit the coals.

Gordy

Wouldn't you be a knuckle head for installing 125' of fintube on one zone in the first place?..........

Steamhead

Hatterasguy said:

Steamhead said:

Hatterasguy said:

Do you know how many licensed contractors in NYC use giant pumps on HW and have a DT in the weeds and make the same comment.........."I've been doing this for 30 years and never had a problem?"

The sad part about this business is that THEY are the problem.

Let's just agree to disagree that "the customer was much better off".

They obviously never saw my article!

But let's get into some specifics. How much radiation, in EDR, was on these systems? What size pumps did they use?

One specific installation had about 125 feet of fin tube and they used a Taco 0010 for the zone. Probably get a DT of about 8. They like the Taco 0010. Never get into any problems when they use it.

But that wasn't a gravity conversion, right?

SWEI

The pump we replaced was a 1/2 HP Taco 1611 1/2HP (80 GPM at 5 feet.)

Steamhead

Hatterasguy said:

Gordy said:

I do believe that Frank's article was written before the onset of DT circs, and DP circs became common place in the industry.

As for balancing, and getting by with a smaller circ. I think one needs to be aware that spending possibly several visits to the site is costly. Obviously the owner would have to absorb these costs since the contractor would go broke with complimentary system balancing. That would be if all valves operated correctly.

I really think that for the time the article was written that the observations, and remedies were the cheapest most effective solutions for both the owner, and the contractor.

You do know that Frank installs steam systems and that ALL steam systems require balancing if they are to function with any comfort whatsoever?

Sure, you can make the argument that balancing isn't cost effective and one should just slap in whatever works in one day and collect your money and run.

However, there are thousands of contractors out there that do exactly that and simply deliver heat. We, here at HH, have developed a practice of bashing said contractors unmercifully provided they are not part of the community. Otherwise, we defend them.

Getting any system to operate well is time consuming and requires effort.

We balance systems when required. This is obviously more of a need on the typical steam system than the typical HW system. Customers want even heat.

But under-pumping a gravity conversion, as I've noted, can cause unbalanced operation. Why would you want to deliberately unbalance a system?

Gordy

SWEI said:

The pump we replaced was a 1/2 HP Taco 1611 1/2HP (80 GPM at 5 feet.)

Now that's a big pump.......

4Johnpipe

@hot rod and @Hatterasguy yes those things you mentioned will work at "one point in time". That perfect "design day". Remember the example was 1 zone which equals 1 thermostat. The situation I described is quite common.
When we deal with this we need to remember everything changes and that never changes.
Why would we not use a circulator that can sense the ever changing loads and adjust its speed to accommodate these changes?
The design may have been wrong. Sure they could run to each room every day and open and close the top vent on the emitter. Or they could benefit from a circulator that could guarantee an average water temperature through the zone.
The room loads will vary of course depending on characteristics. However the rate of heat loss is relatively constant.
Granted the room with the thermostat will be the most comfortable they will not suffer from over pumped emitters for the bulk of the season.

Steamhead

Hatterasguy, let's get back to my earlier question: How many of these systems have YOU, personally, worked on?

I think I know the answer.............

Paul48

Sometimes the best defense, is a good offense.

Steamhead

Whether or not you have worked on these systems has everything to do with this discussion. If you have not- which I suspect- then, unlike many others in this thread, you do not have the experience to back up what you're saying.

Kind of like in this thread. Note especially our Moderator's comment:

http://forum.heatinghelp.com/discussion/comment/1438827#Comment_1438827

Paul48

I have only worked on one of these systems....mine. I have the problem with dropping the most remote radiator, if all the radiator valves are fully open. The answer to my problem, was not to put a larger circ. I just throttled the radiators closer to the boiler. So, I respectfully disagree with the "Deadmen". Of course, I can't blame them, zoning had not come about yet. And, now-adays, just like you leave skimming duties to the homeowner, you can have the homeowner help with balancing. It has to be done. I've held off responding until now, because I don't have time to survey the radiators, and gather all the info that may be needed. I think if you put everything in perspective, and look at the time-frame, you can see where the "Deadmen" would be looking for answers from the pump manufacturers. Unfortunately, by todays standards, the answer they got is poor.

That's just my unprofessional opinion.

Harvey Ramer

I was only gone for the weekend. Tucked away in a cabin in the mountains with no cell or Internet service. It was nice!

Looks like the thread has grown. Lol Lots of great topics, each deserving their own thread to be thoroughly discussed.

The most recent about gravity pumping; @Steamhead is correct on this one. When you measure up the EDR of the radiators and plug in the hydronic formula, sizing the pump for a 20degree delta-t, it works. Everyone gets heat and the homeowner is happy. The additional electrical consumption of the larger pump versus one sized for the building load, would likely not pay for one service call in a 10 year period.

I thought a lot about emitter loads changing with outdoor temp even with a constant Supply temp and flow rate. It is my position that any emitter that is strictly convection will not change in output, however, an emitter that has a combination output of convection and radiation or one that is strictly radiation, will absolutely change in output with the outdoor temps.

Gordy

I fully understand both sides of the argument. The question becomes how much time does a contractor spend to get it perfect. Perfect is Hats perspective. Nothing wrong with that, and I'm quite sure with enough devoted time it would work. That time involved is greatly dependent on how the potential systems condition is.

Time is money. when it comes to the three bid owner that needs the work done who will they choose? Obviously perfect is more involved than better than what was there so that bid will be higher. If better than what was there makes the owner a happy customer compared to what they had I get that. If you get the job, and can talk them into perfect so be it.

Frank put some time, and effort into a theory that does work, and has some substance that can be applied with out much effort with an edr survey. It's not perfect, but it does give results that are most likley better than what they had.

The savings of perfect is not a heck of a lot unless you can drop to an ECM circ. Most likley in a constant pressure mode setting with constant circulation as Kurt has done. In his example savings were quite measurable. With a drop from say a b&g series 100 HV to a taco 007 in a bang bang set up not so much. In the end the owner has heat to all rads. They saved on electric due to the smaller pump that is still over pumping compared to perfection.

Now if we are strapping a mod/con to the system then Hats stand point has even more substance to get the con out of the mod. But with ci boiler not so much..

Harvey Ramer

This topic really deserves a thread of its own.

Hat, we all know you are intelligent and we respect your opinions.

I'm with steamhead on this one and have always been.

Steamhead

Paul48 said:

I have only worked on one of these systems....mine. I have the problem with dropping the most remote radiator, if all the radiator valves are fully open. The answer to my problem, was not to put a larger circ. I just throttled the radiators closer to the boiler. So, I respectfully disagree with the "Deadmen". Of course, I can't blame them, zoning had not come about yet. And, now-adays, just like you leave skimming duties to the homeowner, you can have the homeowner help with balancing. It has to be done. I've held off responding until now, because I don't have time to survey the radiators, and gather all the info that may be needed. I think if you put everything in perspective, and look at the time-frame, you can see where the "Deadmen" would be looking for answers from the pump manufacturers. Unfortunately, by todays standards, the answer they got is poor.

That's just my unprofessional opinion.

In many cases, the valves are stuck, and the owner doesn't want to replace them all. When this happens, you can't balance a system that way.

Steamhead

Hatterasguy said:

I consider your statement that I have no standing in this discussion simply because you believe I have not worked on these systems as a personal attack. You have not a whit of evidence of what I have worked on and I have no intentions of informing you of same.

Then we have no way to evaluate your position. Like most members of this board would, I've posted my background so others can evaluate my position. There is no reason you should be afraid to do the same.

Hatterasguy said:

Either you cease with persisting in this useless argument and provide some support that you can ignore Δ T in your CI installations or I will report your behavior to the moderator.

As far as I am concerned, you have installed countless CI systems that are overpumped and you have no understanding of how to control them without the utilization of excess flow.

Will you unequivocally support and abide by whatever the Moderator decides?

Paul48

Ya know...........One thing the moderator said was that we were here to learn from one another. How can we learn from each other if we can't disagree? No person that visits this site, should have to "show his/her credentials" for stating their opinion. Keep in mind, some of the most brilliant minds in hydronics, don't necessarily have hands-on knowledge, and the things they say are not less factual. This practice, as of late, I find very distasteful.

Harvey Ramer

Hatterasguy said:

Harvey Ramer said:

This topic really deserves a thread of its own.



Hat, we all know you are intelligent and we respect your opinions.



I'm with steamhead on this one and have always been.

NP. You both can overpump to your heart's content. A DT of 12 proves the case. You'd like to be at a DT of about 30.

Plenty of company in that department.

BTW, did you happen to catch the comments by Anthony Renkow regarding the use of a DT pump on an overpumped CI system and how much fuel he saved?

Also, if you have any further doubts, contact Rich McGrath and he can cite chapter and verse on how overpumping CI will cost the H/O significant fuel penalties.

Sure, it's anecdotal but do you really want to ignore it and continue overpumping for the rest of your days?

Have I ever said anywhere that I prefer to overpump cast iron boilers? I think not! You assumed that. It doesn't make it true. I'll have you know I consistently get name plate, or within 1 point, efficiency ratings out of them. Not to mention long run times and minimal losses due to condensing.

In a high mass system with a cast iron boiler, I decouple the system from the boiler via primary secondary. This allows me to pump the system correctly to whatever flavor the emitters might be. On the boiler side I use a Callefi boiler protection valve with a 130° element. This allows the boiler to jump out of condensing mode within a minute or 2 and then stay in a peak operating condition, with an average of 140° water temp for the majority of the season. On a single zone system my boiler will turn on at a call for heat and not turn off until the thermostat is satisfied. My HXer's stay clean year after year maintaining the efficiencies that were measured at install.

Further more, to say any rad system whether gravity or otherwise should be run at a 30° dt is just not good information. Every system needs to be looked at in detail to decide the best approach mechanically. The best approach businesswise, is what will satisfy the customer and make you a profit at a price everyone agrees on. You give the customers good options and they decide what's right for them.

Harvey Ramer

I'll have my cake and eat it too.

Pumping a system at a 12 degree DT and the boiler at a 20 is easily done via decoupling.

Steamhead

Paul48 said:

Ya know...........One thing the moderator said was that we were here to learn from one another. How can we learn from each other if we can't disagree? No person that visits this site, should have to "show his/her credentials" for stating their opinion. Keep in mind, some of the most brilliant minds in hydronics, don't necessarily have hands-on knowledge, and the things they say are not less factual. This practice, as of late, I find very distasteful.

Paul, I get what you're saying. But in the interests of clarity and repeatability, along with many professionals who post on the Wall, I make a point of not only posting results but also what I found when I got there and how I got those results. You can see this in the articles cited above, as well as in threads I've started. To do less would be a disservice to everyone on here.

So it's not unreasonable to expect that from other professionals. We deserve no less.

By implying that I don't have an engineering background, Hatterasguy implies that he does. Since engineers are professionals by definition, we deserve to know how he got to the position he is taking: What research has he done? How many systems has he tried his methodology on? What were the results? What, if any, problems did he have? I have answered all those questions already.

But he doesn't want to tell us. So we have no basis to evaluate his position. He can label the rest of us over-pumpers if he wants, but that means nothing until we see the basis for his claim.

Paul48

It would make no difference, if he told you he had been doing gravity conversions his whole life. The only relevant is the facts he is basing his opinion on. If his facts are incorrect, then provide him with the correct information. There's no reason for any name-calling, or challenging someone's credentials. It's give and take, find the common ground, and that's where the truth lives.

Steamhead

Au contraire- it would definitely make a difference. He has challenged my experience and methods without revealing the basis for his. So I've given the thread the basis for my experience and how I arrived at my methods. That is the standard here on the Wall. In order to make his position meaningful, he needs to do the same.

And, as I've pointed out, this is not the first time he- or someone else- has done this. And this is not the worst I've seen- we've called out some outright lies that were posted here in the past.

It's up to all of us to make sure the information posted here is accurate.

Paul48

There's no arguable response to that.......Everyone here can go back and see what was challenged, when and by whom.