zoning a monoflow set up?

Mike T., Swampeast MO

A well-balanced diverter-t system is likely the most highly engineered residential hydronic system--as such be VERY wary when tinkering.

That said, IF you can keep the zones with multiple baseboards in their CURRENT order, there [shouldn't] be a balance problem as the relative temperature and pressure drops should remain quite similar. If you have to change the order in the new loops you should re-engineer/re-size.

The flow rating of the zone valves compared to the required flow through the loop should determine the size of the valve used--other than slightly increased cost I can't imagine that a ¾" vs ½" valve would affect performance--that is as long as both are adequate to the flow...

Coils often have a much greater restriction to flow than other heating devices so that may or may not cause a problem. Elevation really doesn't matter though--the static pressure of a closed hydronic system has already done the work of lifting the water and the circulator just makes it circulate--up/down is essentially irrelevant. It's the pressure drop through the piping and device that matter.

Be VERY aware of "micro-zoning" and attendant problems in the layout you propose. "Basement bathroom" tends to make me think VERY low heat loss. At best, your boiler would short cycle like mad if that zone alone called for heat--at worst it could be damaged because of extremely low flow. A buffer tank may well be called for. IF your hot water coil is running nearly constantly this might help. BUT, then again, you said that it is low output and if running constantly it could well create "micro-zoning" problems of its own...

steve novak

I would like to zone my system in my home(ranch with finished basemant). Currently I have one zone, it is a hot water cast iron baseboard system with divertet T's. I would like to make the master bed room one zone, the bath and other 2 bedrooms a second zone, the remainder of the upstairs (kit, living rm, dinning rm, hall way) on the third zone, the basement bath the fourth zone, the basement the fifth, and a hot water coil that is in the attic the sixth zone. The purpose of the hot water coil in the attic is to temper the air for a electronic air cleaning system that I installed last summer with my A/C system, the coil is sized only to temper the air it sould not add much heating to the home. I read Dan's book Pumping Away and I plan on moving the pump to the supply side so I would like to do all the piping at once. I had planed on building a manifold and using zone valves to control the flow. I wanted to know if I can leave the monoflow set up on some of the loops the second zone and the third zone because they will have multiple sections of baseboard on them. The other zones will be one section per zone so I planed to bring those back to the manifold. My second question is that the baseboard is feed with 1/2" copper I was planning I using 3/4" zone valves off the manifold is this overkill sould I just use 1/2" valves? My third question is if I sould install a second pump for the attic hot water coil. I have a taco 007 pump and I was worried about the head preassure to the attic in addtion to the other loops all running on one pump, it is about 13' to the attic from the boiler? any opions would be appreciated.

Uni R

A H.O.'s Opinion

Steve, I was wondering about what your goals are in your zoning project? If your monoflo system was well engineered and you have even heat throughout the house (less the normal kitchen factor - which to me would be the most important room to have it's own zone and isn't in your proposal), then your goal would most likely be energy savings. The typical house has minimal insulation zone to zone other than stratification of different floors. What will happen with zoning is that the more heated rooms will be bleeding to the less heated rooms so you may be putting a little less energy into heating the envelope because you are applying the heat where you feel it the most.



Question 1
You may want to look at your situation like this.

A. I need completely independent control of every zone. Then do what you're doing but it may be best to pipe each zone as a loop and scrap the monoflo. The monoflo will make it harder to purge and harder on the circulator. It will also make the system look hodge-podge to the next person who has to deal with it.

B. I want to be able to easily reduce the heat in different areas on a varying basis. In this instance, (remote) TRVs attached to the radiators in some key areas might be a simple solution with no added running costs.


C. I have a good idea of how I want to rebalance the heat on an ongoing basis. In this scenario, maybe install a bypass between the T's on circuits you want less heat on. Install a globe valve on it. You can also control the flow directly through the radiator itself, but you may end up with velocity / head issues since the T's aren't getting to divert what they where designed to do.

It's key to keep in mind that there should be major benefits to zoning since you are adding significant complexity (along with a lot of your time and effort) to a system where reliability is a key requirement. Charles Lindbergh crossed the Atlantic in a single engine plane because it reduced his chance of experiencing an engine failure by 50% from flying a twin engine airplane (btw he also knew a twin couldn't have done if one engine failed). Additionally, zoned systems make far more small requests of the boiler, and this will affect its service life, so you really should be sure of your goals for zoning.


Question 2 - I would pipe 3/4" all the way and then reduce going in to the rads. Less chance for noise and better ability to change circuit layout afterwards or piping into replacement rads.


Question 3 - A closed circuit is like a ferris wheel. The water coming down helps to pull the water going up so it isn't a factor.

Firedragon

I have 4 zones in my

home, one series loop, one fan-coil and two mono-flo's. I will not mess with the mono-flo zones, the dead men knew more than I ever will, FACT!

With that said, the only thing I did to two rooms that would overheat due to improved windows and insulation was add non-electric zone valves. I did that with 10 years experience in the business, after 26 years more I stopped where I should have, FACT!

steve novak

the order will stay the same on the rads. I could combine zone 2 and 3. All that I realy want to do with the main level is keep my bedroom at a much cooler temp at night approx. 60 degrees. So I could pull just my bed rooom off the loop. There is about 15' of cast iron baseboard in the master bedroom is this too small of a run to have on its own zone.

I agree that the basement bath would definately be micro zoning I think it would only need about 5' of fine tube if I did the heat loss calc right. Would I be better of installing a electric radiant mat in the tile since it is not a very large space.

steve novak

Yes the current system seems to be well engineered I have even heat throughout the home. My main goal is the keep the master bedroom at a lower temp 60 degrees at night. The basment does not have heat currently and the hot water coil is not piped yet, so the system needs some changes anyway that is why I was going to break down some of the main living space. This was only for a comfort reason not for energy savings. The basement I would like to have on its own zone for a savings reason. I Would like to keep it around 63 degrees and just turn it up to 68 when it is in use. But the basement bath will be in constant use so I wanted to keep that at 68. The basement will be heated with two cabnet heaters.

steve novak

would I be better off with a Primary / Secondary loop system for this set up or would that be over kill

Tony_8

zoning monoflo

I would use a TRV on the Master BR. That will limit your room to that setting, but not over your main stat's setting. Don't forget the bypass !
Your idea of electric mat in basement bath is, in my opinion, excellent. I've used them with success.
If you zone your basement, DHW, and main living space seperately and have adequate circulation from one circ I'd be surprised (mildly). You might need to zone with circs. I don't think P/S is necessary.
Enjoy your project !

steve novak

Why do I need a bybass with the TRV. wont the flow just go on to the next rad. Thanks for the quick responses

Tony_8

tees

are restrictive to divert flow. No diversion, still restrictive. System flow overall will be less w/ TRV closed w/o bypass. 3 port TRV is in order.

Mike T., Swampeast MO

TRVs on Diverter-T System

Deleted that 1st paragraph--EEEK, what was I thinking?

A bypass shouldn't be needed but...

Diverter systems work because of an intentional pressure drop to divert water, you MUST select a TRV valve with an extremely low pressure drop. Look for the HIGHEST "cv" rating you can find. "cv" is the number of GPM that can flow with a pressure drop of 1psi so a bigger number is better in this situation. Adding the valve can be tricky depending on the style of the b/b radiator.

Since your goal is to REDUCE the temp of your MBR, you can likely get by with just installing a TRV on that b/b. Those baseboards down the line shouldn't be affected too greatly. Just don't forget that you tinker with a diverter-tee system at your own risk! Unless you have the original plans or you reverse engineer the system, seeming minor changes can affect the system to a surprising degree.

Electric floor warming would likely be a very good choice in your basement bath. Not too difficult to install. Very good comfort and reasonably inexpensive to operate in a small space with little heat loss.

steve novak

can I use a three port zone valve instead so I can control it with a wall mounted programable t-stat

Uni R

> Yes the current system seems to be well

> engineered I have even heat throughout the home.

> My main goal is the keep the master bedroom at a

> lower temp 60 degrees at night. The basment does

> not have heat currently and the hot water coil is

> not piped yet, so the system needs some changes

> anyway that is why I was going to break down some

> of the main living space. This was only for a

> comfort reason not for energy savings. The

> basement I would like to have on its own zone for

> a savings reason. I Would like to keep it around

> 63 degrees and just turn it up to 68 when it is

> in use. But the basement bath will be in

> constant use so I wanted to keep that at 68. The

> basement will be heated with two cabnet heaters.

Uni R

Ideas

Would a setback thermostat help for getting the master to 60°? You might just want to run a bypass for that rad or even try just closing off the rad to some degree and see what happens. With well engineered systems it will be like squeezing a balloon. You may have some difficulty getting the temperature difference if the surrounding 65° rooms can easily heat that space. For the basement bathroom, some electric in floor might just do the trick and be simplest. That's a very small area. Insulation in it's walls will help with keeping that bit of heat there and also with privacy for "the moments". The cabinet heaters will be fun. How much head would it add if you redirected the return to pass through them before getting back to the boiler? You could also do a secondary circuit with circulator off the return near the boiler and have it run if it needs heat when the rest of the system has the water heated up. That gives you an easy way to have a second zone. It's not a true zone but it's heating target would never be higher than the rest of the house. Either way, you may need some boiler protection. One thing to keep in mind is that the heat you add to the basement will slightly reduce the heat you have running aroun upstairs.


One thing for sure, I wouldn't mess with the monoflo. Add circuits off the end of it, but don't hack it anywhere. Best of luck, I'm interested in you telling us what you decide to do.

Tony_8

absolutely