How to Adjust Bypass Flow for Boiler Protection/Efficiency?

When my dad’s VF3000 was installed in 2008 we had no boiler knowledge and therefore relied on the installer for our design and install. Along with other things I would change if we were to be installing this today is that the installer did not plumb the return to both return ports on the boiler and also did not install a boiler bypass. Hindsight has me aware of all the things we would do differently today only due to my education through this forum.

Three zones are slant/fin baseboard and one zone consists of three cast iron radiators. Unfortunately primary/secondary piping was not incorporated at install. DHW coil is installed. The VF3000 does a good job of maintaining the 74 degree main floor temp my mom insists on maintaining in the 1940’s 2500 sq. ft. moderately insulated home. The radiator zone in the basement is kept at about 65 but when that zone calls for heat during extreme cold days the boiler takes a pretty big gulp of cooler water and then a longer than normal time to recover.

This winter seemed to allow this issue to rear its head a bit more than prior years. My plan for the summer will be to try to provide additional boiler protection with the addition of a bypass and along with the bypass incorporate the dual return port piping to try to maintain a more constant temp throughout the boiler. I also plan to insulate the supply and return lines to the basement radiator zone. I see from examples where to insert the piping and valve but what is not clear is what determines the final % open/closed position of the bypass valve? How do you determine or calculate how much should bypass back to the supply line and how much should be allowed back to the boiler? Would this valve need adjusted from time to time to maintain a constant as outside temps fluctuate just as you may need for air and coal feed when outside temps drop drastically? I read where it says trial and error but what am I really looking for in regard to too much bypass flow or not enough?

Thanks! Mike

This job isn't

blanchem wrote: trial and error

Its adjust -- test - then repeat - get a non contact thermometer and do a search in these threads for system balance

oh and using one or both return ports - It Depends!

We are comfortable with the boiler operation during the spring, fall and 95% of the winter weeks. I may be anal in trying to achieve 100% satisfaction by means of protecting the boiler. I’m asking if anyone believes the other 5% is achievable by means of the boiler bypass & valve. The comfort level in the living quarters is more than acceptable and my concern is with the basement zone only. There are NO manual valves in the basement radiator loop including NONE at each radiator to adjust for any balancing attempt. As soon as the basement thermostat calls for heat the zone valve opens and into the return line and onto the boiler starts the flow of cool water from the three cool radiators in that loop.

So rather than a bypass valve should I be considering the installation of a manual valve in the basement loop? I’m assuming throttling back this new manual valve in the basement zone would slow up the flow which would in turn allow the boiler more time to recover temp by not losing its temp so quickly? The basement is unfinished so a slow rise in temp there would not cause any discomfort. I’m not an HVAC technician, engineer or a plumber so if the suggestions I make are off the wall please bear with me! This is why I am posting here… I’m looking for help, suggestions and options!

As for the non contact thermometer, what temp difference should I be looking to achieve across the bypass valve should I install that valve?

Not sure what you are referring to when you mention the second return port. This boiler only has one return port and its 1 1/4". There is a second tap near the return but it's for the boiler drain. I believe it's a 3/4" tap.

Tarm sells an automatic bypass valve for just this situation. Check with Brian at Tarmusa.com

You can also look at a Danfoss ESBE valve. If you look at the ESBE valve section on the Danfoss website, it goes thru the whole thing pretty thoroughly. It's what I use.

Yes. Didn't know if it would be advantageous to pipe additional return into that port while adding fittings in the pipe to retain the drain? Thought since I would have to disconnect the 1- 1/4" to install the bypass plumbing anyway it may be worth while adding that?

Thanks Guys! I'll research those valves.

Yes Please do your reading. There is no one or two line answer that I or anyone else can print here to answer your questions correctly. Yes you have written a considerable description of your drama - but even that simply scratches the surface. I have written a considerable composition of prose or verse --- several times --on system balance - it also is just a kiss to a bigger drama that cannot be explained in a few simple words.

Every install and problem is different. I am not suggesting you need to go out and hire a plethora of lawyers guns and money - but you do need to read the books - search the threads - arm yourself with a few simple inexpensive diagnostic tools - and discover for yourself what your comfortable with in infrastructure enhancement expenses vs 'possible' result.

Then -- and only after - you will be able to ask succinct questions and get a wealth of good advice from figments of the public internet.

Kind Regards
Sting

Pinegrove coal user & oil man, Thank you both for your one and two line answers to my drama. They were both informative enough to help in my quest to continue toward a solution that works for us. People like yourselves offering up real world, what worked for you advice is what the forum is here for and what you hope for when posting for some help. Although it would be great to have if available, people are not always expecting the holy grail of answers when they post. They are not looking for enough knowledge to write a thesis. They are looking for advice, suggestions and what worked for others in similar situations.

Sting, I don’t post much but I do read a lot. In an attempt to educate myself on a subject I have interest in but not thoroughly educated on I have read enough of the NEPA posts over the years (I believe I have read them all a couple times) and due to that extensive reading of your answers to posts when I wrote my initial post you were the last guy I was hoping for an answer from and the first one to answer. Although a lot of your posts appear informative I don’t know if you are trying to dazzle the members with your brilliance or baffle them with your bullshit but many of your posts do nothing for the OP other than a desire to never post for help again. You may or may not be a professional in HVAC and if not maybe you are just the kind of person that can read a book on any subject and immediately have all the answers but please keep in mind that others may not be as fortunate as yourself.

I am a professional myself but in another field. I have worked on computers and networks for over 35 years. I feel sometimes I can fix them in my sleep but when family, friends or even strangers ask for help I try my best to help them. I don’t tell them to go buy or read books on the history of the computer or make them feel belittled for asking for help when they have little to no clue how a computer works. I hope they are truly stuck and have done as much of the research that they can before they ask for my help but even if that is not the case I usually go out of my way to fix it and if I’m remote I do the best that I can to lead them in a direction towards a solution. Just like this site… all free of charge! I hope my real world experience suggestions are just as valuable to them to go along with any book they read on the subject. If they try my suggestion(s) and have no success and come back for more guidance I may roll my eyes when they are not looking but I try to offer additional suggestions. If they fix their issue I’m happy for them and get satisfaction in that I could help. If I didn’t want to help I’d stay silent.

I’m not looking for an online pissing contest I’m just handing out a little of what I hope is constructive criticism. Feel free to belittle at will as you have done to others who have questioned your remarks in the past. Long winded as I am, I have said my peace. You are welcome to a rebuttal as all my reading of past posts suggest you will but out of courtesy to the members don’t expect any follow up from me.

Wow and ouch. Sting is a font of knowledge and offers it freely. No one can give you accurate advice on your system without really seeing it. Sorry your expectations were not met and frankly Sting doesn't need or want me to defend him. But I think you were alittle harsh. If you really expect help here you might want to consider not pissing in the punch. Since you are apparently going to tackle this modification yourself, he just wanted you to understand what you doing before picking up a wrench.

Blanch,

X 2 and 3. Ive oft thought the same and am find myself somewhat ashamed I havent said so. just trying to get along I guess.....

waldo

coalkirk wrote:Wow and ouch. Sting is a font of knowledge and offers it freely. No one can give you accurate advice on your system without really seeing it. Sorry your expectations were not met and frankly Sting doesn't need or want me to defend him. But I think you were alittle harsh. If you really expect help here you might want to consider not pissing in the punch. Since you are apparently going to tackle this modification yourself, he just wanted you to understand what you doing before picking up a wrench.

Straight up answers are always nice, but may not be accurate depending on many variables. A true professional like Sting knows this, and would rather throw you a riddle or two, which makes a person think for themselves. Like CoalKirk says; Sting wants you to take a good look at your system, and try to understand what's going on. Not be a parts changer. Now for my un-professional opinion; 1.) I don't believe you need a dual return line. A bypass loop should keep the boiler water stirred up. 2.) For them few cold days, restricting water to the cellar radiation may work, or, put a switch in the basement thermostat wire. Turn the switch off during those bitter cold temps. Or, if your thermostat goes low enough, simply turn it down. I'm assuming you have the basement on it's own zone. 3.) If it's lag time you're concerned about, simply maintain a little bigger idle fire during them bitter cold periods. Oliver

Could something along these lines be utilized? See attached PDF drawing.