Mixed Emitters on Manifold

nosirra1Arrison

Are there any rules or methods that need to be kept in mind when you have mixed emitters on the same manifold? In this case it is 6 underfloor w/plates radiant loops (all 250ft) and 4 loops with oversized panel radiators w/trv. Manifold (CROSS Manifold zone valves) has balancing valves w/flow meters. Pump is an ALPHA.

hot_rod

It comes down to what SWT the various emitters need to give you adequate output. If the required temperature of the various emitters is within 15° or so, no need to add an additional mixing device.
If the panels require say 140F or higher on design day, that might be a bit much for the underfloor plates, you may get hot spots and striping, uncomfortably warm floor surface. 82°F is about the high point of surface temperature for a residential system. Above that you start to get sweaty feet.

Panel rads usually have derate tables or formulas to show output at the various SWT. Say you are limited to 120F on the plates, what can you expect from them panels at that same temperature.

Here is an example

nosirra1Arrison

The panels are type 33 - 24x71. Sized for heat loss at 130 degree design day. Coordinates with radiant. I am prepared to use supplemental heat if needed in panel rad area.


My concerns are about the manifold connections and ecm pump.

Should the manifold connection order matter (radiant loops/panel loops)? Is reverse return needed? How do you reverse return panels and radiant on a single manifold?

I guess I will need to use proportional speed two on the Alpha to service the radiant loops. I know the "zone valves/panel rads" would like to use Auto adapt. Any ecm ideas for mixed emmitters.

Anyone who is interested in the topic of mixed emitters may want to review this article:
https://pmmag.com/articles/102613-john-siegenthaler-mixed-emitters

TAG

Have always used the bypass fittings when using the panel radiators -- my memory is the load of panels is about 12k btu per 1/2 pex loop. This way each unit can modulate with it's own Danfoss head -- they each get full temp water from the ODR. It's really nice heat if you can position the panels correctly

So you are using the Cross with a sensor in each room for the panels?

My new renovation project has a large living room ... 1000sf that we are using retrofitting plates. I'm going to use a Honeywell thermostat with both room and floor sensor for that space and two zones of slab. The floor sensor is a high temp limit.

I'm using 3 cross manifolds .... not up and running yet. Those Cross are slick

hot_rod

Is it a homerun piping, where every heat emitter has it's on manifold connection? If so, no need to use a bypass H valve.
The bypass H valve is for radiators in series.
I imagine the Cross manifold has flow balance for each loop?
130° SWT for design day on the panels sounds reasonable. Did you do a load calc for them plate radiant, what temperature do they require? That of course varies with floor coverings, I think the 130° may be close enough and a one temperature system should work fine.

I'd say Grundfos and Taco are the brands with the most ECM options. You may need to play with mode settings to find them one that matches your installation best. No harm in switching between the modes until you find the one that covers your requirement. That's why they offer all the mode choices

TAG

The Cross do have both gauges and the balance valves.

He mentioned using the TRV on the radiators ... so that confused me ?

I have to say the Cross manifolds are very nice --- my installers were very impressed. Since you have control over each loop zone built in to the manifold --- along with the simple interface to a thermostat. The system is very simple and clean if you want full control over each loop. Even on my slab where I have 8 loops and each area is 4 loops ..I would need 8 thermo heads on the standard manifold to control each .... by the time you get all the parts the Cross starts looking better as they are expensive.

IMO -- the nice thing about the panels is being able to string them together and have the head on the unit modulate for the temp in each area .... I have two in many rooms and they work great.

Alan (California Radiant) Forbes

@nosirra1Arrison:
Sounds like you did your homework. Panel rads sized at 130° - perfect!

nosirra1Arrison

D

TAG said:

So you are using the Cross with a sensor in each room for the panels?

I have only 3 zones for the 6 underfloor radiant loops that service the upstairs. 4 of the zone valves are jumpered on the Cross control to combine the Great Room loops into a single zone. Be careful not to make individual room micro zones that have low btu loads. It WILL cause boiler cycling. I learned that lesson long ago.

hot_rod said:

Is it a homerun piping, where every heat emitter has it's on manifold connection? If so, no need to use a bypass H valve.
The bypass H valve is for radiators in series.
I imagine the Cross manifold has flow balance for each loop?
130° SWT for design day on the panels sounds reasonable. Did you do a load calc for them plate radiant, what temperature do they require?

All homerun loops. I did one pair of downstairs panels in series (a small bathroom and smallest bedroom). That is the only bypass valve loop. I did several heat loss calcs for the radiant upstairs. I also got the real life btu calc from my previous staple up that is being replaced. The real life was just slightly less than the calculated heat loss. Radiant temp is calc at 130 at design, due to vaulted great room ceiling and carpeted bedrooms. Real life performance is the true measure. Calcs are our best educated guesses.

nosirra1Arrison

TAG said:

The Cross do have both gauges and the balance valves.

He mentioned using the TRV on the radiators ... so that confused me ?.

I have TRV on each panel with homerun back to manifold. I run boiler on outdoor reset and try for near constant circulation. I let the TRVs police the radiator temps but if I sized them ok I may have the TRVs set wide open.

TAG

The different houses where I used my panels they ran off off Buderus CI boilers. The panels being the primary loop off the boiler -- the manifold directed the 1/2 pex to different areas of the house with the use of the diverter valve on the bottom of the radiator -- with the Danfoss head fine tuning. The manifolds were wide open and just used for connection. The diverters are not cheap little things ... but they work great.

Some loops had 2 panels others 3 -- depending on load. On one big house I did over 20 panels.

I had to use a mixing valve to lower the temp for the floors in the newest area of one house. In the other I had tiles and use a floor thermostat. I also oversized the panels to lower the temp.

nosirra1Arrison

TAG said:

So you are using the Cross with a sensor in each room for the panels?

The Cross Manifold has homerun to each panel radiator (except one vertical paired with an oversized). Each panel radiator has a TRV. There is ONE central thermostat that is jumpered on the Cross Control linking all the panels. The thermostat will act as a high limit only. TRV's will run the temperature control.

hot_rod

Guess I'm wondering why you need a zone valved manifold with a single thermostat controlling all the loops?

nosirra1Arrison

There are two types of emitters on the Cross Manifold.
Plate underfloor radiant (6 loops) for upstairs.
5 oversized panel radiators downstairs.
All homerun.
The radiant upstairs is zoned with 6 loops total. 4 loops (Great Room) controlled by a thermostat as a high limit only - 1 bedroom loop with its own thermostat (high limit only) - 1 more bedroom loop with its own thermostat (high limit only). So there is more than just a single thermostat.
Downstairs has just one thermostat for all the panels. It acts as a high limit only also.
All boiler supply water temperature control is done by outdoor reset. This is a one temperature system that runs on near continuous circulation (Alpha2).

nosirra1Arrison

I could run this with no thermostats at all (just outdoor reset), but I do have solar gain in the Great Room and I also do not use one of the upstairs bedrooms much.

nosirra1Arrison

I should have been clearer in the earlier posts about which loops off the manifold were hooked to the underfloor radiant and which loops are hooked to the panel radiators.
The Cross Manifold is an elegant simple solution to my system where half or more of the zone valves stay open the majority of the time. Once valves open the Cross Manifold uses almost no power vs. a zone valve that stays powered nonstop. The manifold comes equipped with goodies such as drain ports, shut off valves, balancing valves and is pre-wired in a simple clean manner. Well worth the cost.
Here is the manifold with just the plate underfloor radiant hooked up.

nosirra1Arrison

Here are a few pictures of the oversized panel radiators and Cross Manifold/Alpha setup. The panel radiators run at the same temp as the underfloor plate radiant for upstairs. Clean and simple.

nosirra1Arrison