What is a venturi loop system?

Brad White_9

a Monoflow or Diverter-Tee system. Look those up here under "Heating Q&A" and under that, "Diverter-Tee Hot-Water Heating".

Daniel J. Doerpholz

What is a venturi loop system? And other system problems

I recently bought my first house and I had the boiler cleaned because it hadn't been done since it was installed (about 6 yrs.) The boiler is a Weil McLain gold series that burns #2 oil. The tech that cleaned the boiler told me that the boiler was pretty close to being undersized, he said that the input was 75000btu's and it was turned up to the max. I also had him look at the heating system and he said it was a venturi loop system, I have looked high and low and can't find any info or description of what that is. The house has cast iron baseboards and a couple of newer hydrotherm radiators as well and I don't think that they where installed correctly. To make a long story short the house is very cold all the time, and the boiler comes on runs for about 15 20 min and shuts down the thermostat is a new honeywell and I have it set to 65F and the boiler will run but the temp won't increase unless I turn it up to around 68F and let the boiler run for about an hour. It has 1 taco 007 circ pump on the discharge side of the boiler, the pressure stays around 12-15 psi can anyone offer me any advice or explain what the heck is a venturi loop system? also the house is about 1800sqft and has baseboard on almost every wall (even some interior walls) is this unit undersized?

Unknown

I'll do the best

As others will explain better, I'll do the best I can... Venturi system have a main loop with one supply and one return to each radaitor from the main, above main radaitors will have a special fitting called venturi tee on the return side, which have a small funnel-like part inside, causing the pressure difference flow thru the radaitors. The cast iron baseboard is considered the 2nd best emitter in comfort. Mixing the possible you have copper finned radaitors with cast iron on the same zone is a big no no... Your heating system may be sized correctly but at what the boiler temps? What the temps on the bolier gauge? The colder outside, the hotter you'll need....

ralman

Daniel

This link Has some excellent info on venturi tee heating system courtesy of our distinguished host Dan Holohan. Sounds like we have similar heating system problems.

http://www.heatinghelp.com/heating_howcome3.cfm

Norm Harvey

Have you tried bleeding the individual radiators and baseboards through the coin vents? (Us heating guys LOVE to bleed)

Also you could check to make sure all of the valves on each end of the baseboards (inside the enclosures)are open.

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

Christian Egli_2

This is the right place to look

You're in good hands when the Ace Venturi Heat Detective Crew gets on the case.

Daniel J. Doerpholz

boiler water temp(s)

When the boiler runs the temp varies between 115F to almost 170F, it depends on how long the boiler has been running. If I set the thermostat to say 64F the boiler will cycle for about 15 to 20 minutes and then shut down and the temp on the guage won't get over 120F. When the boiler isn't running the temp of the water inside the boiler drops down to below 70F (I can't say what the exact temp is because the gauge only goes down to 70F, but the needle is pegged on 70F) I blead all of the air out of the radiators using the bleeder valves on either the end or the side of the radiators. All of the radiator shut off valves are open. I have also made sure that the pressure is correct (between 12-15psig) after I have blead all of the radiators. When the temp. on the thermostat is set and I don't turn it up to around 70F the radiators never get hot or even warm.

Daniel J. Doerpholz

I have blead all of the air out of the radiators using the bleeder valves on either the end or the side of the radiators. All of the radiator shut off valves are open. I have also made sure that the pressure is correct (between 12-15psig) after I have blead all of the radiators. When the temp. on the thermostat is set and I don't turn it up to around 70F the radiators never get hot or even warm.

Dale

baseboard

I think your boiler is large enough, you can run it up to 200 degrees ( actually 240 but 200 is more reasonable for a top number) if you need to but I don't think you do. You should start at the easy stuff and make sure the air openings to your baseboard are open, I can't tell you how often a boiler gets blammed for carpet tight under the baseboard or closed rad shutters. Where are the tees to the rads? If not under each end you may not get good flow. Then invest in a pros time or start with a good contact thermometer and see what temp the water is actually leaving and returning to the boiler, usually 190 out and 170 back. You have a monoflo system so a spirovent air separator is a good investment. The pro will check that you are not on one giant loop, maybe you need a repipe, but, start with the easy stuff first and get some data. good luck

Unknown

t think

I think the pump is not working.... Time to get a REAL boiler pro to check it out...

rob brown

if i had to guess,

i'd say the taco 007 is probobly to small. monoflow tees work by increasing pressure drop thru the mains and forcing the water thru the branches. depending on how many rads. and length of run, the pump cant push hard enough. rob

Tony_23

Thermostat

Sounds like it's short-cycling the stat. I fyou set it high enough it runs an adequate time to bring up room temp. The anticipator is likely set too low, or the stat is in abad location.

Joe Mattiello

Venturi Tee fittings

You mentioned having baseboard around the perimeter of the house. Calculate the flow required to satisfy the load at approximately 600 btu per foot of baseboard. Divide that by your delta T X 500 for flow. Now you can calculate the frictional losses through the piping, and the additional pressure drop through the venturi tees collectively. I have attached catalog data for the Taco Venturi Tee fittings to help you with your computations. after you have finished with the calculations select the pump that will meet your design using the published performance curves. I have attached a pump selection manual to help you.