TRV and Venting

hvacfreak2

I'm considering some Danfoss TRV ( vent style for 1 pipe ) , is there a specific vent that works better for these ? Or at least a different strategy than we would typically use ? Thanks for replies.

ChrisJ

It depends on the setup.
I have a Gorton #5 on one of mine, and a Gorton #6 on the other. Both are the straight connection type which sadly only come in their painted gold color.

You need a fast enough vent to heat the space normally, but not so fast that it overshoots and doesn't give the TRV time to react. What vent is currently on the radiator and how does it perform overall?

hvacfreak2

What vent is currently on the radiator and how does it perform overall ?

Hoffman 1-A set to a chart from an old " DM Steam Class " , Dan rattled off the 1-A cfm settings as we discussed the chart. I have all of my 1-A's set to that chart except for 2 downstairs that I put D's on this year and will probably switch those back soon. Most upstairs are set to a G5 or a G6. I did purchase the venting pdf but it has not arrived yet.

My upstairs radiators just do not need to perform all that well simply because those rooms are unoccupied most of the time. I would just go with a Hoffman straight adjustable ( 1-b ? ) but the cost is a little bit out of line on those for some reason.

JUGHNE

I have used Hoffman #41 vertical vents (I believe) on 1P TRV's.
They were chrome plated, not too expensive. Faster than a 40.
.125 cfm for 41 and .087 cfm for the 40 @ 3 ounces.

But a vacuum breaker is needed. Not all TRV's have the vac bkr built into the control and require an add on.

hvacfreak2

10-4 on the vacuum breaker , the Danfoss valves include those. the 41's were catching my eye for the cost , thanks for the feedback on those.

ChrisJ

All I can say is,

JUGHNE

These are probably for guest bed rooms.......same reason to not have an empty closet in there or to have the king size sleep number bed there..........some guests have an expiration of welcome date, so a few sounds in the night.......

But they would be impressed by the nice chrome plating!

Bio

If boiler matches the radiators EDR, steam will almost never reach the vents (vents will last longer) of course the exception is the one design day, radiators are already oversize for the room they're in, there is no need to fully heat the radiator, running the system in ounces is key

Mark N

That's very true Bio. My radiator vents never close. My boiler is well matched to the radiation which is oversized to the heat loss of the house. I don't use setback either so the boiler never runs long enough to completely heat the rads across.

hvacfreak2

Mark N said:

That's very true Bio. My radiator vents never close. My boiler is well matched to the radiation which is oversized to the heat loss of the house. I don't use setback either so the boiler never runs long enough to completely heat the rads across.

And exactly why controlling the system based solely on a single setpoint room thermostat with a fixed differential is a waste ( fuel usage ), I'm working on that. And that also makes me think that it may be best to go slow on the first floor venting and faster on the second floor with the TRV's. I'm thinking that if the TRV element is calling for heat than it's best to get steam to them first so that they will close. So , I'm thinking that I need a really fast , inexpensive vent for the TRV's ;

supplyhouse.com/Varivalve-VASA-Varivalve-Adjustable-Straight-Valve-3841000-p

Bio

I would use the same air vent on all and let the trv do the work, I like Macon trv's, they use ventrite air valves and the vacuum breaker is on top, out of the condensates way, solid unit

http://www.steamdepot.com/OPSK.html?id=BxwLvfIy

ChrisJ

Be warned even when those trvs close the radiators will continue to heat until the cycle is over. They will stop increasing in output but continue at whatever amount that was filled with steam. I found 2 cycles per hour works really well with them.

hvacfreak2

ChrisJ said:

Be warned even when those trvs close the radiators will continue to heat until the cycle is over. They will stop increasing in output but continue at whatever amount that was filled with steam. I found 2 cycles per hour works really well with them.

Yeah , I can see that , thanks. I'm imagining these are a rather
" passive " control depending how far down they are adjusted maybe. Also I'm curious about the Danfoss vent as well.

ChrisJ

I have two of the Danfoss TRVs, but none of their vents. I recall their vent being a cheap vent made by someone else, but can't remember who right now. Either way it's nothing special.


You can get the TRV to throttle the vent speed somewhat, but you can't rely on it. Meaning if you need a Gorton 5 vent and you put a D, it's guaranteed to overheat constantly or not heat at all if the TRV doesn't call for heat.

If you have a long runout to the radiator (2nd, 3rd floor etc) I recommend venting the runout separately and keeping the radiator vented on the slow side. I did this for a while but going to 2 cycles per hour eliminated the need on my system

You'll see once you start using them. They work well, but they don't work exactly the way I expected them to meaning I assumed I could put Gorton 6s or Cs with them and have them 100% control the heat. Doesn't work that way, they're too slow and once the radiator has steam in x number of sections, it'll continue to heat that much until the system shuts down.

Another odd thing about mine, but need to be set to between #1 and #2 to keep the rooms in the high 60s. I have one set to #1 and it maintains around 64F in the room. No idea why, but it doesn't match the chart they give you.

hvacfreak2

I just got all of my information together , G.Gills pdf and I found my old workbook and my venting calcs. for all of my radiators.

Thanks for the insight as to how those work , much appreciated @ChrisJ. From my old calculations ( cfm / 4 @ 2 oz) I am at Gorton numbers 5 and 6 for the upstairs , slightly more than a
H 41 at 2 oz. At 3 oz the 41 gets real close , if I close down the 1-A's downstairs to match the 3 oz column the system may be ...a bit slower ? But perhaps more " even " ? I have 1-A's up there now I may " trial run " that before the radiator valves go on.