Add a Danfoss ESBE Thermic valve to my FrankenBoiler?

Syncro

I have a Weil McLain Gold 5 that ran about 10 years with an oil burner and then was converted about 6 years ago to a Carlin EZ-Gas running propane. The unit was installed when the house was new, but when I asked the builder to scrap the heat pump and install hot water baseboard instead, he neglected to get an actual boiler guy to do the work. So it was installed by a few AC guys that "always wanted to install a boiler...". I ended up buying a copy of Dan's book (still on the shelf) and getting the piping worked out so we were "pumping away" and I fixed the makeup water with my new knowledge about the "point of no pressure". It has been ok, but just. There are 6 htg zones, 4 of which are used regularly plus indirect DHW. I have DIY'ed this thing along the way with a Honeywell AQ control strapped to a Taco 6 place zone valve control. Now that I am taking a closer look, I am seriously wondering if the installer switched the Taco circs. There is a 010 on the 6 heating zones and a 011 on the DHW. In looking at the specs, this seems like it might be backwards and I question if the 010 moves the water fast enough, especially since the Honeywell reports as much as 50 deg delta T with only 2 zones open. So last year when I had some time I purchased a Danfoss ESBE Thermic valve and the thermostatic cartridge with the idea that I would create a loop to prevent water < 135 deg in the return. It's still on my shelf because the circ question is nagging at me and I'm wondering if it's worth shutting it down and switching the circs first. The house is about 5,000 sq ft and I did a heat loss/gain calc some years ago which I probably can find if the info is helpful. I underfire the EZ-Gas by one size since a friend/HVAC guy thinks the 185,000 net IBR is too big. I have read so many thorough and well thought out replies on this site so I'd love to hear what you pros think.

icesailor

Head Pressures:

IMO, its more important to know what the differential pumping pressures on either side of the circulators so you know how many GPM's are flowing through the circuits.

A Taco 010 will deliver a 30' head but only 10 GPM. So, at a 30' head, there is little flow.

A Taco 011 will deliver a 30" head and 30 GPM's. 

Pressure is " in head X .434. 30" head equals 13# PSIG. At half the pressure head, the 010 delivers 5 GPM. The 011 delivers 15 GPM.

1 GPM equals 10,000 BTU's per hour.

You can't calculate unless you know the head pressure required to overcome the resistance of the system. A 30 degree Delta T is a lot is pressure drop with either of those circulators.

IMO.

Syncro

Time for calculations

Thanks, ice for pointing me in the right direction. I suppose I need to dig into the head calculations. What is a target flow rate, in other words, what is a "good-range" and would generally support the optimum delta T? When I calc feet of head do I include the sum of all the zones? or just the longest zone? I'll start measuring...

icesailor

Regular Vs. ECM's

The sum total of all zone's running is usually considered the boiler load. The pump has to be able to deliver that load.

For discussion of the short bus route, say that a system has a calculated and proven load of 150,000 BTU's. But it has three zones of 50,000 BTU's each. The circulator has to be able to deliver that amount and more to do the job. If only one zone is calling, the circulator is 66% oversized etc. That's why ECM's work so well. They ramp up as needed. Or ramp down.

Understand that I am technologically an mathematically challenged. I just understand the concepts. Some here are far more into the finer points than I. I just made them worked and fixed them when I could. If it could be fixed.

icesailor

"Head calculations":

Trying to do theoretical head calculations give me a headache. If the system is already there, do what I do and get the real time head pressure on the pump. You can never go wrong.

It's like the IBR ratings on hydronic boilers. If you size to the IBR ratings, piping and pick-up are already added to the rating. They also state that if there are unusual situations, you may have to add more. The IBR ratings have never let me down. Its a good place to start.

Syncro

Max flow rate for 3/4 copper too low?

Ok, I took a look at this calculation using the taco instructions. Right off the bat, if I calculate flow rate as 150,000 BTU over (500 x 20), I get 15 gpm. According to their table, 3/4 copper can only flow at 6.2 gpm max. So with 3 zones open, I could get 5gpm per zone and achieve the 15gpm. Am I thinking about this correctly? The 010 can support only about 8 ft of head at 15gpm but about 12' at 5gpm. Do I size the circ using the 15gpm or use worst case = 1 zone and use the max 6gpm? Thanks.

Syncro

How do I determine the pressure?

Ice, I'm confused. I think I see how to calculate the head, but I re-read your post and I think you are suggesting to just determine the pressure on both sides of the circ. How do I do that? Do you mean to actually take pressure measurements?

icesailor

Pipe sizes:

Your Weil-McLain boiler is tapped 1 1/2 NPT on the supply and return. You pipe the supply and return to meet the demands of the system load. I don't remember what the rating for your boiler is but 1 1/4" would probably be the largest size you need to pipe. Maybe even one  (1") inch. A rule of thumb used is that 3/4" copper tube is good for 35,000 BTU's, 1" is 65,000 BTU's and 1 1/4" is higher. I don't remember the exact number at this moment, But it is a rule of thumb. It is similar to having a 1" water service come into your house but the pipes get smaller as they go to fixtures that all are fed by 1/4" or 3/8" risers to the faucets. If you have the Weil-McLain installation manual for your boiler, it will say what size is needed for the load of your building. As far as the circulator, it accepts up to 1 1/2" flanges. The largest rated boiler of that series with the largest amount of sections can not deliver more BTU's than can go through a 1 1/2" pipe. But all front sections are piped with 1 1/2" IPS for manufacturing convenience.

Some installers will pick a size like 1 1/4" or 1" and make a manifold. All take off's to the zones are from 1 1/4" X 3/4" black tees. It doesn't matter how many take off's there as long as the base manifold is properly sized. It is hard to undersize it but then, common sense isn't a monetary value.

icesailor

Pumping Logic:

Don't overthink the issue. Pump "head" and pump pressures are a confusing issue.

As a well driller and a heater, I have a completely different understanding and use for head pressure, I will try to explain. If you have a well and it is 300' deep but 100' to water, and the water will flow into the well at rates that take it out of the equation, the pump must develop enough pressure to :push" the water to the surface, 100'. About 43.4# PSIG. But if you want to have enough pressure to take a shower on the second floor bathroom that is 30' above grade and need 50# PSIG pressure. So, the submersible pump has to develop enough pressure to raise the water to 126#  BUT WAIT!!!.

What if it is NOT a submersible pump and instead, a Jet Pump. That sits on the ground. And is where it compares to the circulator pump in your heating system. "Jet" pumps can only lift water from 33' theoretically and 25' practically. So you put two pipes with the "Jet" device on it and put it in the water. When the pump starts, it circulates water down one pipe and it is easily pushed back up the other pipe. But it only has to push the water back up the pipe far enough for the pump to "pull" it up the rest of the way. For every 4 gallons of water the pump sends down the well through the injector/jet, pressures and vacuums sent 5 gallons up the pipe. Then, the pump has to develop excess pressure to push the water to the desired pressure which is called "Head" or, how high the water would be in a pipe that went 100' in the air', If you had a tee in the 100' pipe, every 10', somewhere, there would be a point where water stopped running out of the tee. That's "Head Pressure". The farther up the pipe you go, the slower the flow because of a lack or pressure/volume.

This is simplistic. If you comprehend what I have written, think of your heating system like the two pipe water pump.  The water is constantly circulating at the top of the well through the pump, but the water level in the 100' pipe above it is equal to the head pressure.

In heating systems or potable water systems, if you connect a 3/4" garden hose to a sill cock, and the hose is 25' long, it will take you a measurable amount of time to fill a 5 gallon bucket. If you add a 75' X 3/4" hose (now 100'), it will take a measurably longer amount if time to fill the bucket. You can measure it in Gallons Per Minute. You can make them be equal by raising the supply pressure. That pressure is called "Head Pressure" because it is the same as the water level in the 100' pipe.

I hope that's understandable. No one taught me. I had to figure it out when I was trying to figure out why something I had nothing to do with didn't work. And my classes for my plumbing exams. Interesting stuff.

Syncro

Makes sense

@icesailor- Thanks for the explanation. It helps. Also, now I understand my submersible and jet pumps on my wells much better! I took a crack at calculating the ft of head and I am planning to call Taco today to see what they say. On the surface it sure looks like the 010 is undersized and in addition there is a 011 on the indirect HW which is MASSIVE for a head of less than 1! I see some changes ahead. Thanks again. --Dale

icesailor

Pumps:

Switch the pumps.

Then call Taco if you need to. I doubt that you will need to.

Raise the pressure in your system and if the problem doesn't go away, change the pumps. They aren't perfect but they should be doing the job.

Think of it this other way.

You have dissolved oxygen and nitrogen in your blood. If you don't use nitrogen in your daily function, you ain't of this earth. Our atmosphere is 80% Nitrogen, 20% oxygen.

If you do a scuba dive to 100', all the oxygen and nitrogen in your blood are compressed. When you come up to the surface, the pressure is lowered, and bubbles will form. If you don't rise slow enough and let the bubbles be absorbed, they will move to your lungs, heart and muscle. They cause what is called "The Bends". It can kill you. The cure is to put you in a hyperbaric chamber and put you under pressure. Causing the bubbles to be re-absorbed by the blood. If you rise slowly, the body will slowly absorb the air bubbles.

Look at your heating system like a diver with the bends. At the bottom, there is enough pressure to keep the air bubbles compressed. As the fluid water gets higher in the system, the pressure drops and the bubbles form. If there isn't enough pressure at the top of the system, the pressure can go negative. It will cause bubbles to form at the top of the system. Raise the pressure and the bubbles will be compressed and absorbed.

IMO, if you use a high head circulator that isn't needed (like a 011), and the pressure isn't high enough in the system, you run a greater chance of the pump forming bubbles in the impellor of the pump. Its called Cavitation. The bubbles end up at the top of the system. Another reason that circulators are nice on the returns, contrary to ALL advice. The hotter the water, the more cavitation and the greater the cavitation. The boiler may be a more expensive air eliminator than a Spirovent, but it works better than a Spirovent. All those Air Scoops that myself, others alive, and all the old dead Wetheads used years ago on the supply with circulators on the returns, with no air problems. I have to ponder that.

The same noise you hear in your well pump if you hold the pressure switch plate down so it doesn't stop. At 20# PSI, the pump is quiet. If it is a single stage pump (one impellor), then, 50# is the best you can hope for in a new pump. But after it gets to 55# PSIG, it won't pump water anymore and the pump starts to make a wooshing noise. The noise starts at between 40# and 45# PSIG. That's cavitation. Inside the pump where the impellor is spinning, bubbles will form because of negative pressures.

Some of us have figured out that putting a high head, high volume pump on a undersized, under designed system is the same as putting a band aid on a roaring infection. Smaller or just right is the best. Too big can create problems.

IMO, the method of finding out the pressure differential on either side of the pump is the best and only way to figure out the actual head pressure in an installed system. I always stayed within the parameters of the piping rules. Then checked the differentials. They were always within the parameters. When I was checking bad systems, I found some that were out of the parameters and using high head, high volume circulators to overcome bad piping practices.

Syncro

New circ on its way

Well I had a nice talk with Joe at Taco today who agreed that the two circs are not correctly sized. I am going to drop a 007 in the DHW circuit and use a 014 Delta-T pump for the heating zones. This has the flow required with all zones open but will throttle back when needed. Knowing pexsupply, it will probably show up tomorrow and I'll have a weekend project! Going back to my original question, if I still have low return temps I'll consider the ESBE Thermic valve. Otherwise it's for sale. Thanks for the help.