Radiant heat

Plumbkeith

If i wanted to install 3 zones of radiant heat. Would i need three seperate mixing valves. Or can i have one mixing valve before 3 seperate circ pumps?

SWEI

That's a rather broad question

but in general, it depends on the emitters.  If all three are sized for similar water temps, then one reset curve will work just fine.  If one is baseboard, one is CI radiators, and the third is RFH, you will most likely need three mixing valves, each with its own reset curve.  Probably.  Why three pumps?  Why three zones, for that matter?



More info please...

Plumbkeith

Radiant heat

They want one zone for kitchen, one zone for living room and one zone for dining room. Whats the best way of piping that off the boiler. Or should i make that all one zone?

Zman

Why all the zones?

To answer the original question. It really depends on what type boiler and and how it is piped.

Unless I am missing something, it should all be on one zone. Unless the rooms are closed off to each other or have drastically different solar exposure or heat losses, they should be on the same zone. Separate zones will cost extra money and reduce overall efficiency due to short cycling.

The owner is always right, unless they are wrong. Then it is your job to explain it to them.

Carl

Rich_49

Give this a look

https://www.box.com/shared/ffbszrqfa4

SWEI

Still too many zones for my taste

A well designed single zone system with a properly tuned reset curve can produce amazing comfort.  We frequently see ~1F variation across an entire heating season this way.  Using a room thermostat to switch water (which may be only a few degrees above the air temperature) on and off is a recipe for unhappy occupants.



We use conventional zone valves as high limit controllers for problem situations: Where there is significant solar gain, a woodstove, or other heat source, and also for deep setbacks (rooms or wings which are infrequently occupied and for which a long warmup time can be tolerated.)

Gordy

Agree with zee, and swee

But some questions are not answered. Is the three spaces in question open concept?

Is the radiant emitters already in place? How many sf are the rooms in question? How does solar influence each room?



Does the client understand the extra cost associated with zoning verses not?



Sometimes people think they are in control of their energy consumption by zoning. When realistically at times it can create an influx of heat loss to adjoining zones increasing energy consumption, or decreasing comfort to them.



In a room combination you are talking about as far as living function these rooms are usually used in conjunction with the activity of cooking eating, and lounging after eating. So why control separately .

Rich_49

It was not

all the zones guys . It was more a guide to what can be zoned together and water temps . If he zones them all separately he may use one Mixing device because as each is satisfied flow will stop and floors will not overheat . I do question 3 pumps though . Why not use one pump and 3 zone valves .  To answer the original post .  If all 3 areas have similar use patterns , similar finish floor R values , and similar BTU sq ft requirements , zone them together .  And answer Gordy's questions for your benefit