Diverter/Venturi tee system questions

SuperTech

One of the few things I am still wondering about after reading Dan's books concern my system at home. I have big plans for when it gets warmer. I'm moving my circulator pump to the supply, obviously going pumping away. Im switching to a Taco VT2218 variable Delta T circulator for a few reasons, I'm adding isolation flanges, Spirovent and a few valves I'm also. Building a four zone manifold for the supply and return, one 1 1/4" zone for the Venturi tee loop, a 1"tee stubbed out for a future indirect and. 3/4" zone to add some cast iron radiators to a finished basement room.
Well my Venturi tee loop is reverse return, cast iron baseboards emmiters. I was wondering if TRVs would work with this piping, or is a crazy idea?
One other question, with a two pipe diverter tee system like mine, would a Venturi/diverter tee be required on both sides of the radiators below the mains like in single pipe monoflo?
Thanks for any information or suggestions, Any recommendations are welcome.

newagedawn

yes, you would need a monoflo tee on every radiator if you were to add trvs

newagedawn

i'd start with the circulator first and see how it runs, you might be surprised and find you dont need the trv's

SuperTech

> @newagedawn said:
> yes, you would need a monoflo tee on every radiator if you were to add trvs

I have one on the supply pipes to each emmiter, I know that it would be better if they were on the return. I'm just wondering if the rule about having one on both sides of the emmiters when they are below the mains applies to two pipe and reverse return systems.
Currently it works with just one, but whoever installed it put fin tube convectors downstairs when the rest of the house is cast iron baseboards. And it doesn't heat the room. That's why I plan on upgrading to cast iron radiators and zoning the boiler.

The TRV question is just because I'm wondering if it's possible, I like the additional control they offer.

I'm really looking forward to the re-pipe and trying out the VT2218.

ScottSecor

Are you sure your system is reverse return with venturi (monoflow) tees? In most cases we see one or the other but rarely both, especially in the same loop. In my area many homes and commercial sites have monoflow systems. Very few homes have reverse return system, most larger commercial systems have this setup.

From your description, I think you might just have a monoflow system (without reverse return). If I'm correct, you need to consider a few items, first each monoflow tee is equal to twelve feet of pipe. The second thing to consider is that there isn't all that much velocity going through each emitter. That being said, you may have trouble with using TRV valves as the flow may not be adequate to pass through the rather restrictive TRV, especially if there is a long length of pipe to and from trunk to the emitter.

If I'm mistaken and you do in fact have reverse return, then absolutely use the TRV valves.

SuperTech

It's reverse return, first emmiter off the supply is the last to return and the last one off the supply is the first to return. I've seen examples of this piping with diverter tees in Dan's books, but the diverter tees are shown on the return pipe. I suppose mine is a "push" style system rather than a "pull" style with Venturi/diverter tees.

I'm not really worried about flow, I'm sure I can dial in the new Taco VT2218 ECM pump to do the job, as it is now the 007 on the return is providing adequate flow.

GBart

Cut it all out and zone it, I had a 100 year old house, one summer valved off the boiler for h/w and cut all black pipe out, re ran small copper and zoned it, it was a small house with one radiator in every room, I split it to 1stfl, 2nd fl zones and made a 3rd the bathroom, let me tell you how nice it is to wake up and have your bathroom set where you want, I had a 8gpm everhot in the top of the boiler with tempering valve for h/w teeing off as a bypass to the return and to the zv's, all left over parts from installations.

It worked great, would I do it again? maybe, but I always zone my bathrooms as a separate zone now

SuperTech

As tempting as it is to rip out and scrap all of that 1-1/4" and 1" copper, I don't think I can bring myself to do it. I like my cast iron baseboards too much, and I can appreciate the design of the system with it's Venturi tees and reverse return design.

I have a cast iron radiator in my bathroom. Maybe I could "zone" it with a TRV?

newagedawn

please dont get rid of your cast iron rads you will regret it !!!! forget that joke off !!!!!
add the spirovent with the circ on the supply side and ill bet you wont need to add all the rest of the trvs, unless you want to control each room, thats an expensive desision for the control

SuperTech

I only have the one cast iron radiator, the rest of the house is cast iron baseboards, with the exception of the finished room in the basement that has fin tube convectors. The fin tube is going to go. I would never get rid of the cast iron baseboards!

GBart

newagedawn said:

please dont get rid of your cast iron rads you will regret it !!!! forget that joke off !!!!!
add the spirovent with the circ on the supply side and ill bet you wont need to add all the rest of the trvs, unless you want to control each room, thats an expensive desision for the control

I never said get rid off the radiators or any cast, I said the black pipe, at that house it took one low limit cycle just to get the pipes warm, it's not efficient at all, at all.

GBart

I miss my cast iron radiators terribly and cast iron baseboard rocks, but in these old houses they over sized black pipe and you are wasting btu's heating it and the gallons of water they contain, I found I needed very little btu's to each overall as this was a small house, to zones with 2 rad's I came out the 3/4 zv and then split to 2, 1/2" lines, the bath one 1/2" line, if you don't need the btu capacity of 3/4 it's a waste of energy, the system rocked my fuel bill was nothing. This was just something I did at my own home over the course of a winter, not for everyone, at the least insulate the hell out of those black pipes or any supply pipes.

In my present home I spent one winter in the attic super insulating and installing a Unico system with a huge perimeter loop which is the best way to go, again, time consuming.

Solid_Fuel_Man

I would try the circulator as well. I'm not sure why a reverse return would want/need venturi's. I'd be tempted to just cut out those venturi's and make it a normal reverse return if you are not satisfied with performance. A blocked up branch off a venturi system adds SIGNIFICANT head, so TRV's may not play well if they are left in.

I love reverse return systems, perfectly self-balancing with one or all branches open.