Mixing Hoffman and Gorton's

mgmine

I have been following the thread

Can there ever be too much Main Venting

And have a similar problem. I just installed 2 Gorton #2 vents on one main and 1 Gorton #2 plus 1 Hoffman #75 on the other main. Both mains are about the same length and same pipe size however the one with the 2 Gorton's heat up quicker. Is there a problem mixing a Hoffman and a Gorton?

Mark_125

I'm no expert...

...but I think its more likely that the difference in the venting capacity of the Gorton #2 vs the Hoffman #75 is the reason for your imbalance. I believe the Gorton has way more venting capacity than the Hoffman. If your mains are almost identical in size then they will need identical venting to evenly balance.

I have two mains similar in size and due to height restrictions use 2 Gorton #1s and a Hoffman #75 on each.

Patrick_North

Mark is right.

That Gorton vents at more than twice the speed of the Hoffman. If the mains are similar, put one of each vent type on each main. Not a problem to "mix and match." In fact, the somewhat different properties of these vents make for a good pair- you get quick venting, but also a vent that is quick to reopen as main temperature dips back down. Nice, even venitng.

Good luck,

Patrick

Rod

Main Vent Mix

Hi- I agree with Patrick. At first the higher venting capacity of the Gorton #2 was very inviting to me (and still is!)  However the Gortons open/close around 145 degrees, where as the Hoffman 75 opens /closes at around 180 and as Patrick mentioned, in some cases the properties of the Hoffman may make it a very beneficial mix with the Gortons. My main vents are located just after the last radiator lateral and as this radiator is a bit slow to heat up, I've been wondering if maybe all the air in the main isn't completely out when the Gortons close and therefore the radiator vent has to vent the remaining air from the main.I haven't done it yet but am thinking of adding a Hoffman 75 to the Gorton #2 to see if that makes a difference. If the main vents were located on the boiler end of the dry return this wouldn't be a concern as any residual air would be in the dry return part of the system.

- Rod

mgmine

Add a 3rd vent?

Well since I have 1 Gorton and one Hoffman on the one main would adding another Gorton to the mix create a worse problem (2 Gorton's and one Hoffman)? I hate to just ditch the Hoffman but since I have 3 Gorton's and only one Hoffman I can never have a match on each main without buying 2 more vents. Do you think I would be better off just leaving things as they are? I'm not as concerned about both mains heating at the same time as I am about wasting oil.

rcrit

Main Vent Mix

The other feature of the Hoffman is it closes with an audible "clink" when it closes which, at least in my case, can be heard throughout the pipes. It tells me things are working. Interesting that they operate at different temperatures, I didn't know that.

Patrick_North

A few questions.

Well, let's back up a little.

* You say the mains are approximately the same length and size pipe. What is the length of each and pipe size?

* You say the main with a Gorton and Hoffman is venting slower. How much slower than the one with the two Gortons? Better question- once the boiler starts making steam (steam header gets piping hot) how long does it take for the end of each main to get equally hot?

* Do you notice any problems because of the uneven venting- that is, do the radiators on the slow venting main heat slower than those on the fast venting main?

Thanks,

Patrick

mgmine

Pipe length

The main with the Gorton and the Hoffman is 58 feet long and has two 90 degree elbows.. The main with the two Gorton's is 56 feet long with five 90 degree elbows. The main with the two Gortons heats faster, at least the radiators heat faster, Checking the radiators on the slower side they are all still cold while the other side is starting to get warm. They eventually all heat up but when the heat only goes on for say 1 /2 hour the larger radiator on the slower side is only half warm. 

Patrick_North

OK-

Guesstimating 2.5" main size, your main with 2 Gortons is venting (under textbook ocnditions) in about 45 seconds; the other in about a minute flat. By most standards this is pretty quick, so I'd turn to balancing rather than simply increasing venting.

Knowing that these vents aren't cheap, here's some experimenting you can try with what you have:

* Remove vents (and cap/plug them!) such that each main has a single Gorton #2. Does this solve your uneven heating problem? Great! Now you can consider buying a fourth Gorton or a second Hoffman so each main can have the exact same venting.

*If your mains still aren't heating at the same rate after making the venting the same, try swapping vents so that the one that currently has two Gortons has a Gorton and a Hoffman, and vice the versa. Did this improve the situation at all, or simply reverse it?

*If using equal ventingheats your mains at the same time but you still have uneven heat at the radiator, you can turn to the radiator vents themselves to address balance issues.

This venting stuff can seem like voodoo. The (cheap! worth it!) e-book available through this site demystifies it all, and you can read it in 20 minutes.

A few other gotcha's come to mind. Are both mains well insulated? Could one or more of your main vents be faulty? Do you know how your boiler's EDR capacity (size) compares to the total EDR of the radiators in your house? More simply, do you know if your boiler is substantially over or undersized (usually the former)?

Good luck,

Patrick

mgmine

EDR

The EDR was figured out prior to putting in a new boiler last year so it's pretty close. The insulation is the same on both mains. I will try the idea of swapping the Hoffman from one main to the other and see if it changes things. If it does then I'll probably just let it go and concentrate on venting the radiators. Thanks

Patrick_North

Equalize it to start

I'd test the effect of equal venting first, even though that means removing a Gorton and Hoffman. Sounds like the steam is following the path of least resistance and starving one of the mains.

It's really difficult to fix main venting issues by adjusting radiator vents.

Good luck,

Patrick North

mgmine

no luck

I took all the venting out on the side that heats quicker and installed the Gorton #2 and the Hoffman 75 on the slower side and the side with no vent at all still heats faster. Not a lot but faster. Ant thoughts?

Enreynolds

It seems

That your mains are actually venting through through the radiators, rather than the main vents.  This points to your radiator vents being way too fast.  Steam will take the path of least resistance.  you could shut off all the radiators and fire the boiler to test the main veinting to see what kind of pressure you are running while venting, and balance the main venting first, then begin balancing the radiators with some slower vents.

Eric

Jeff_44

Yes,

I had the same issue. I started the thread about "Can there be too much main venting" and as I tried things, I learned that I was allowing FAR too much venting in the radiators. Once I backed things off, the main I was having trouble with filled with steam just fine. Now things are MUCH more balanced.



Good Luck

mgmine

very litte heat

I will shut off all the radiators on the main that is heating quickly and see if that helps. I noticed this morning after 1 hour of running the radiators on the far side were only slightly warm. I'm not sure what is meant "you could shut off all the radiators and fire the boiler to test the main

veinting to see what kind of pressure you are running while venting" Are you saying to look at the gauge on the boiler and see what the pressure is? 

Bio

Venting

I suggest trying what I did, first close all radiators valves, second remove all main vents to the 3/4" tapping and from a cold start clock how long would it take each main to reach steam at each return tapping and that would tell you what your goal as far as how fast can you vent, if your mains are 2" a G2 and H75 is more than enough, radiator venting may be creating a system inbalance, my new boiler matches very close to the radiator's EDR and I installed hoffmans 40 on all radiators and two ventrites 1 on other two to tame down because of radiator oversized, all my radiators heat up evenly now at 2oz and never cycles and shuts off when the thermostat is satisfied, and by the way all radiators do not get full by the time thermostat is satified