Do I need a bypass on my hot water heating system?

Live/Learn

I Have a Burnham V83 forced hot water heating system. I have two zones, one in the main house (1200 sq ft.) and one in the finished basement. I hardly ever use the finished basement heat as we don't spend much time down there. The upstair zone is a one pipe (1" main) monoflo copper slantfin rad system. My concern is the possibity of thermal shock due to the cold return water hitting the hot water in the boiler after the heat has been off for awhile. My old W.M. never had a bypass and ran fine for 45 years. Also I don't see many systems with bypasses around here. Do I have anything to worry about? Are the new boilers built as good as they were in the past? Thanks in advance , Live/Learn

Weezbo

wow!

a V8? i forgot the question....maybe you need some insulation in your homes ceilling(roof) ...spend a few dollars on new style squishy foam around the windows..down size the nozzel to like way way down, for base board heating unless your way out there on the ends of the btu scale and its all the boiler can do to lose ground to the cold i wouldnt think you NEED a by pass. i put them on new boilers for the last 25 years or so..even though they may not Need one,it allows me to heat the boiler up pretty quick and check all my operations and iam warm while doing it *~/:) i think the last V-8 i installed is heating a Tri Plex...

Biged

Boiler By-pass

Burnham manuals say there should be one dipending one where your expansion tank is located. I did a seminar with Glen Stanton last year and he stressed piping with a by-pass. My only question about this is do I need to pipe 11/2" around the boier all the time or can I reduce to say 1" or 11/4"?

Live/Learn

boiler bypass

Yes , that was going to be my next question . If I need a bypass can I bypass with 3/4" copper as this would be the easiest way out as I already have T's in the right places and won't have to tear down a lot. Thanks for your reply. Yes it gets pretty cold here on the eastern tip of LI, Weezo.Live/Learn

Paul Pollets

Bypass

a full size bypass using a globe valve should be used. If the supply header is 11/4", than use an 11/4" bypass. The return water should be above 130 deg. F. within 5 min. of boiler firing to prevent condensation and/or thermal shock. Don't forget to put in a thermometer on the return past the bypass tee, to be able to tell how far to open the bypass.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Unknown

V8 Bypass

If you have a cast iron radiator sustem then it is indeed advisable to install a boiler bypass. The 45+ year old boiler you had had a much larger water content and took a good long while to bring temperatures up in the system. The newer boilers have a fraction of the water content of the old boilers and in turn can bring up temperatures with much greater efficiency.

The issue has to do with a mismatch in system water content versus boiler water content and the possibility of the boiler/burner running for prolonged periods of time with cool return water. This is primarily a condensation issue within the boiler flue passageways although thermal shock can also possibly become an issue. The boiler bypass will limit the volume of cooler return water the boiler encounters and will allow it to transition through the condensing range much quicker.

Generally a 1" bypass would suffice but it can't hurt to make it bigger. What is important is to have globe valves or full port ball valves in the locations shown below to properly throttle the flow through the boiler and bypass. Visual indicators (Thermometers) are also neccessary to see what you are accomplishing by adjusting the valves. Hope this helps.


Glenn Stanton

Manager of Training

Burnham Hydronics

www.burnham.com

hr

I'll bet

a 3/4" will get the job done. Usually that valve on the bypass gets throttled anyways.

Raypack sends their boilers with a 1/2" copper bypass and ball valve.

The key is to watch the temperatures and balance the valves accordingly.

An infrared temperature gun works nicely for this adjusting.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Weezbo

i am not the manufacturer of the v-8

so let me say something outside the box,.........a monoflow system of 1" is pretty much fulltime circulation,if the supply line to the heat emmitters islike a 1" line then a 1/2" is what i'd consider using, in that you have two one inch lines one for te basement and the other for the living quaters upstairs,..and relatively quick return of a max of 12 gallons no matter what way the wind blew while installing it, know nothing about nothing, i'd feel safe using a 3/4" bypass, and to go one step further out on the periphery an esp set point modulating zone valve would pretty much lock the number in place as it were.

Unknown

Weezbo

Although a properly designed and installed MonoFlo system can help ensure much warmer return temperatures, it is no guarantee that they will be above 140F however. These systems act and perform much the same as today's primary-secondary system but they can be over radiated and improperly sized or installed. For these reasons it is always a good idea to install the boiler bypass (at least) anyway. Hope this helps.

Glenn Stanton

Manager of Training

Burnham Hydronics

www.burnham.com

Live/Learn

boiler bypass

Thanks Glen for the information and the great diagram. I have fin type rads but I see your point. I love my V83 as it's very efficient and also very quiet. I am running it with a beckett burner which I think is a great unit. Thanks again for all you do on this forum. I like your dedication to your company they are lucky to have you. Merry Christmas to all. Live/Learn

steve_29

Glen, have a question...

I notice you have a temp gauge on the supply side of the bypass valve, if you trying to temper the return water wouldn't it make more sense to install the gauge on the return side of the valve?

or am I mistaken.

thanks

Unknown

You are mistaken

There are two types of bypasses, a boiler bypass and a system bypass. The drawing shown is a "Boiler Bypass" whereby the volume of return water that the boiler is getting is regulated but not the temperature. The boiler will still see cooler return water but less of it allowing it to transition through the condensing point quicker and to remain above it with no harm to the heat exchanger.

The "System Bypass" takes heated supply water and sends some of it across the bypass to the reyrn to help warm up the cooler return water. The primary difference between the two types of bypasses is the location of the system pump. In a Boiler Bypass application the pump(s) are always on the System side of the bypass. In a System Bypass application the pump(s) are always on the Boiler side of the bypass. One thing to remember though with a System Bypass is that the capability of the pump to exert its flow to the system will be reduced somewhat because of the increased flow around the boiler itself. Here is a graphic depicting both types of bypasses. Hope this helps.

Glenn Stanton

Manager of Training

Burnham Hydronics

www.burnham.com

Unknown

RE: Need for Bypass

When you mentioned the MonoFlo system with Radiators, I took those to be cast iron radiators. If you have Fin Tube radiation, there may not be a need for a bypass. By watching your boiler water temperature as it is coming on after a setback period or a prolonged off period, you will see if there is a need for the bypass. If the boiler remains at or about 140F for a prolonged period of time then there would be a need for one. Hope this helps.

Glenn Stanton

Manager of Training

Burnham Hydronics

www.burnham.com

Live/Learn

boiler bypass

Thanks again Glenn for your information. After reading your replay I now feel as though a bypass isn't necessary as my boiler gets above 140 pretty fast as I don't cold start but warm start at about 150 which seems to help and I feel is better for the system,don't you think? Live/Learn

steve_29

Thanks