Variable flow injection pumping boiler overhaul...Need advice!

SuperTech

I've been reading a lot about boiler protection and primary secondary piping configurations and I want to try converting my boiler to a variable flow injection pumping setup. I currently have three zones, the main house is on a reverse return Venturi tee split loop with 1-1/4" supply and two 1" returns. Cast iron baseboards. Second zone is a 1" indirect. Third zone is going to be a 3/4" reverse return cast iron radiatiors zone.
I'm planning on a 1/-1/4" boiler and secondary loop due to the size of the Venturi tee loop. I'm wondering about the split loop. Just add another tee to the secondary loop, right? Also I'm wondering what the best size pipe for the crossover bridge would be. I plan on using a B+G autocirc on the boiler loop, a VT2218 as the injection pump and an Alpha 2 on the secondary loop. I've got 90% of the materials needed to do this but I need to reread primary secondary pumping made easy again first

SuperTech

For what it's worth the man I spoke with at Taco said it doesn't matter if I use 1" or 1-1/4". He said that I'm splitting hairs and the pipe size doesn't matter because the flow is variable.

I'm just nervous because as a service technician that deals with residential work I rarely see anything like what I'm considering doing. I'm fascinated by high end hydronic jobs and I'm willing to learn by experimenting on my own boiler, but I don't want to make too many mistakes. It seems like more research is necessary.

hot_rod

need more info. What temperature will you run the boiler

How many gpm on the distribution side and what temperature

With enough delta tee, 1/2 could be sufficient. If you oversize that piping, add a balance valve to get some authority

tekmar has excellent design info for this type of system

SuperTech

The boiler is an oil fired peerless WBV-03. It's rated for 112,000 BTU/hr. .85 80B nozzle. Im using a partial outdoor reset since I'm trying to avoid flue condensation. The boiler is limited between 145-180.

When I did the math in the formula in Dan's book (I read it a second time since my first post) I come up with a desired flow of 7.46 GPM, which means the 1-1/4" is a bit big, and maybe 1" would have been better?

I'm trying hard to learn as much as possible, Caleffi has been a great source of information. I was really hoping you would respond to this thread hot rod.

By the way, could a Caleffi quick setter be used to meter flow on the return bridge?

SuperTech

Attached is the design I chose to base mine on, obviously not everything will be the same. I've been looking at every available image on Google. I find myself staring at them just to find out I'm looking at a chiller.

Hot Rod if you have any Idronics videos that you could recommend I'd appreciate learning anything that would help make my idea work. I was thinking about doing a hydro separator, but that would be too easy. 😉

hot_rod

I'm not sure I'd consider that primary secondary piping? There needs to be closely spaced tees to be true P/S. That is a complex control logic with ∆P sensors and a drive responding to the changing ∆P are rads open and close. Maybe a delta P circulator could do that without additional sensors.

I don't see boiler protection in that piping example? No way to disconnect load from boilers?

How many radiators, how much water in the system, we could project the operating temperature of the system assuming everything starts at 65° for example.

SuperTech

I didn't even think about the spacing of the tees in that picture, I just assumed the the two pipes coming off of the boiler loop were piped in closely spaced tees

Perhaps my idea will not work. The lack of responses to this thread is discouraging

Maybe I should just try a traditional design, with traditional boiler protection methods. I'm just not sure what is best. I was hoping to get the most out of the capabilities of the new ECM circs.

I'm open to all suggestions. I'm definitely going to see what I can learn from Tekmar.

Gordy

I prefer the elegance in simplicity to achieve the goal.

hot_rod

Do both zones get the same SWT?

I'm not sure you have a high mass system that needs boiler return protection? How does the boiler output match the load? If the boiler is a bit oversized I'm not sure that you need return protection. How does it run now?

Take the indirect tank off the boiler as a parallel loop so it sees the hottest SWT on priority.

VS injection 1" balance valve on return, runs on ODR.

No zone valves or TRV in the system, so not ∆P required?

SuperTech

I'm a little intimidated by mathematical formulas because I always stunk at math, so unfortunately I haven't figured out what the radiation is capable of. I don't know how much water it contains, but it's more than some largrr houses I see with fin tube or hydro air.

What I do know is that on most days I can keep the thermosts satisfied with relatively low supply water temps of 145-160 and heat an indirect but I have a hard time keeping return water temperature high enough

I like your drawing hot rod, it's veryy close to what I was thinking about doing.

I have zone valves currently, I was considering keeping them with the Alpha if I go with a manifold type setup, like in the reverse return picture.

@Gordy As a repairman/Service technician I love nothing more than a beautiful simple design. But I'm also fascinated by the complex stuff that I don't normally see every day. I've got the sickness bad, I daydream about hydronic designs constantly! I understand the foundation of everything is to be designed to the load, but I'm pretty sure that the boiler and piping are both probably oversized, but I can only guess until I do the math and measurements.

Zman

Not to derail you but....
Mixing control is much easier to dial in. you don't have to worry about balancing and surging injection pumps. Just buy a valve with a CV rating ~ the same as your design flow, set it up and walk away.
The Taco I series works well for outdoor reset and boiler protection

SuperTech

Zman I have explored that option, I've read that's how they do it across the pond. It does seem like an easy way to achieve the desired results. But protecting the boiler isn't my only goal, I want to fully understand how a variable flow injection pumping setup works, it would be a great feeling of accomplishment if my idea actually works!

The I series is awesome looking, I like Caleffis hydro separators as well. I like anything that allows for precision temperature control of the primary and secondary loops, I think that stuff is cool.

Does this type of setup have too much potential for disaster? Im willing to learn through trial and error...to some extent.

Gordy

Zman said:

Not to derail you but....
Mixing control is much easier to dial in. you don't have to worry about balancing and surging injection pumps. Just buy a valve with a CV rating ~ the same as your design flow, set it up and walk away.
The Taco I series works well for outdoor reset and boiler protection

This what I mean about the elegance of simplicity. With a twist of technology.

SuperTech

I've been spending time tonight looking at some of the more advanced Tekmar controls available. Perhaps I can achieve the temperature control, boiler protection and everything else injection pumping offers with simpler primary secondary piping and a sweet but pricey Tekmar control.
I'm probably going to end up with both now, complex piping and controls, knowing my tendencies.

hot_rod

As you are discovering, it comes down to how much $$ to spend for the pursuit of the “perfect” piping and control marriage.

I have redone my systems, ho e, shop and in laws home a dozen times, several boiler swaps, control and pump testing.

siggy sends me some new piping idea and I try it out in the shop.

My shop has a woodboiler solar, 500 gallonbuffer and combi modcon,

SuperJ

hot rod_7 said:

500 gallonbuffer

Gordy

Mass is your friend

SuperJ

A simple approach would be P/S, with a thermostatic bypass within the primary, and constant circulation on the secondary, with the thermostat firing the boiler to achieve space setpoint.

You secondary loop would basically run at whatever temp the house needed without even using a ODR.

Gordy

Isn't that what happens with simple bang, bang thermostat control?

Boiler runs, or runs and cycles until setpoint is reached, and the water temp ends up being what it is once setpoint is reached.

Depending on load demand. The boiler could run 2 mins, or 20mins. It may never reach high limit, or cycle off high limit. Kind of a simplistic indoor reset.

hot_rod

And always remember the heat emitters are in charge. They dictate the operating condition of the boiler, not the opposite.

Unless you put some influence in the way

The Euro method, one of them is constant circulation, squirt a bit of temperature into the loop occasionally. But TRVs are the common room by room control, a nice wireless solution for even radiator by radiator adjustment.

Eastman

@SuperTech
Import a Honeywell Evo home communicating wireless smart TRV kit and let us know how it goes.

SuperJ

The thermostatic bypass would ensure the boiler gets up to temp and has a reasonable min run time, since the secondary loop wouldn't get any heat until the bypass opened. Some stats like the ecobee let you specify a min heat call time.
The subtle difference I recommended was constant circulation, for most people a zone valve closes or a pump shuts off. Constant circulation keeps things nice and even it lets the high loss zones steal heat from the thermal mass of the lower load emitters.
It would be nice to have a post purge timer on the primary pump to avoid standby losses of the hot boiler. But I guess if not it will just open the bypass quicker on the next run cycle.

You could use nice hydro separator instead of the tees to get some air and dirt separation too.

Love my TRVs.

Gordy

Be careful with trvs that approach you are thinking isn't how it will work out, as far as stealing from other zones. There won't be any stealing from a satisfied trvd zone, or a zone valves zone that is satisfied. There shouldn't be any stealing any where if emitters are sized properly.

Gordy

Now if you have a 500 gallon buffer tank

Eastman

How about this...
No thermostat, instead use deltaT pump in "set point heat mode". So the pump is programmed to maintain a room temperature by either speeding up or slowing down the secondary loop.

SuperJ

> @Gordy said:
> Be careful with trvs that approach you are thinking isn't how it will work out, as far as stealing from other zones. There won't be any stealing from a satisfied trvd zone, or a zone valves zone that is satisfied. There shouldn't be any stealing any where if emitters are sized properly.

Agree, but I was assuming SuperTech has no TRVs just a couple emitters in parallel served by a single pump. Constant circulation helps even things out, assuming the flow is going everywhere.

Zman

Injection mixing is not terribly difficult to set up and when done correctly works great. I think it has gone out of favor due to all the slick, inexpensive mixing setups on the market.
This is a pretty good explanation of how to design the different options. http://www.tekmarcontrols.com/images/_literature/e0021_06.pdf?lbisphpreq=1

They used to have great white paper on injection mixing. It looks like they took it off their website.

SuperTech

Thank you everyone for your input and suggestions. I was really hoping for multiple responses and suggestions.

Unfortunately I don't have TRVs and installing them on 60+ year old cast iron baseboards would be a pain in the butt.

@SuperJ the first thing I tried was a bypass, first a simple ball valve then I put in the VT2218 to pump the bypass. I can get 15-20 degree temperature increase to the return water, but on milder days with shorter cycles it still isn't enough to get the return temperature high enough.

I need to separate the boiler from load and gain better temperature control of each. I love the capabilities of the Tekmar 361 mixing control but unfortunately I can't use the VT2218 with it. Taco claims the pump is capable of being utilised for injection pumping without a separate control, so maybe I'll try that.

This will be the third time I modified my piping design in three years, but I enjoy doing this. It was an article by Siggy on injection pumping and boiler protection that inspired me.

@Zman thanks for the link. That was exactly what I needed.

As you guys can see I'm not an expert and I have a lot to learn so keep the ideas coming please.

SuperJ

You had a bypass before but you never decoupled. A thermostatic bypass would actually decouple the load.
I'm not actually advocating for a bypass over a mix valve or injection pump though.
The advantage of the injection pump or mix valve is that you could have a elegant outdoor reset and boiler protection at the same time.
The main downside to injection is that you need at least 3 pumps plus controls.
The taco I series valve would let you use 2 pumps and is nicely self contained (doesn't need external controls to do its job).

hot_rod

Here are a few different ways to provide return temperature protection.

I think you get more control functions and adjustability with the tekmar controls, but if you already have a VS pump, give it a try.

Also PM mag article on VS bypass pump as return protection caution.

SuperJ

Wow, that sums up the options nicely.
I will say that those six options actually give you two features, boiler protection, and control over the secondary water temperature. If you don't actually need more control over secondary temperature, some of the arrangements could be simplified a bit. The two way valve solutions with a throttle/CBV in the bridge (to create a pressure drop to force flow through the injection loop) is something I wouldn't have thought of.

And no the injection pump arrangement won't work on that tank setup (in the second screenshot). Since the tank pump is still forcing cold water into the boiler return. All the injection pump does is dilute the cold water return with some of the supply water, but the flow thru the boiler is the sum of both pump's flow. If the boiler protection feature was on the tank pump it would work since it would remove the load until the return water comes up to temperature.

SuperTech

@hot rod_7 those six options are awesome, some of those are configurations I haven't seen before. Thank you again!😀

I think I'm going to try the variable speed injection pumping with the vt2218. I have hot water priority control already and ODR but I love the capabilities of the Tekmar controls, but I can't find anything that works with an ECM pump. I'll have to use a less sophisticated control strategy for now.

It looks like I made the same glitch in the article on my boiler. It helps, but I need the control capability that primary secondary pumping offers.

This is all great information. I'm really glad I started this thread.

What about the Caleffi QuickSetter? Can that be used to balance flow on the crossover bridge?