continous curculation

J.C.A._3

> the control has a programed setpoint & outdoor <BR>
> sensor. Supply water temp is "reset" or mixed <BR>
> based on outside temp releavant to the setpoint <BR>
> by the mixing valve. The mixing valve is <BR>
> controlled via the temar unit. All the pump are <BR>
> running constantly; "zoning" & temperature <BR>
> control are accomplished via the danfoss <BR>
> non-electric operators. I'm guessing that the <BR>
> sensors on the return are to protect the boiler. <BR>
> Is the boiler a regular cast iron boiler? There <BR>
> is so much grey area in hydronics... This seems <BR>
> pretty safe though! <BR>
<BR>

salbertj

continous curculation???

Hi guys.Have a lot of qeustions about the above topic.Was in a house that had 3 zones of hotwater heat.Cast iron rads,basebord,convectors ect No radiant.Almost all of these of had Danfoss thermostates installed on them.No thermostates in the house.There is an outside sensor with a tekmar type radiant control in the boiler room.Also there is a 3 way motorized mixer under a 1" copper supply manifold with three pumps that run continously.All the returns come back in a single 1" line that tees off to the boiler,a flow control going with flow into the 1" "mixed" water"side of the three way under the supply header, and then into the "cold"side of mixer in that order.There are sensors on the return to the boiler and under the supply manifold north of the mixer.I qeuss the mixer is there to set a design tempeture for the water.Is this to vary the water temp on different degree days.0 Versus a 40 degree day?Or is it that the Danfoss valves have a better flow rate at certain temp water.Have seen the injector pump type set ups for mixing this is not like that.Anyone feel like talking about this system.Thanks in advance!

J.C.A._3

Think about the .....

Thermostatic radiator valves as a thermostat for each room or zone.

Once the outdoor temperature goes below the setpoint, the circulators start...and continue to run until it gets the signal from the O/R control to shut off, as long as the piping can support this...VERY IMPORTANT!

This is done in lots of the world..and it makes very much sense to me. The draw on MOST of the circulators we would be able to use would be as much as a 75 watt lightbulb...on average. The comfort gained by this type of system is unable to be rated, as far as the customers I have talked to. Each room heats until the valve "tells it" to close down...and the flow just bypasses that particular room until the temp. drops enough for the body of the valve to open for some flow to enter and exit it. What could be more simple?

The outdoor reset control, when properly programmed will "tell" the boiler what temp. it needs to meet the heat load at the temperature it has programmed for,(local design temps.) from its outdoor sensor...making for a SWEET and cost effective system.

For the most part, this works extremely well with high mass radiation, but WILL work with lots of different applications, to your advantage.The 3rd way, on a 3 way valve would be to do a couple of things. #1 would be to keep the boiler from seeing condensing temperatures at the flue...#2 would be to protect the production of hot water....if it was part of the package in the overall heating system. (I keep trying to coin the phrase "medium mass" such as panel radiators...but I don't think it will ever be accepted!) Chris

John_82

the control has a programed setpoint & outdoor sensor. Supply water temp is "reset" or mixed based on outside temp releavant to the setpoint by the mixing valve. The mixing valve is controlled via the temar unit. All the pump are running constantly; "zoning" & temperature control are accomplished via the danfoss non-electric operators. I'm guessing that the sensors on the return are to protect the boiler. Is the boiler a regular cast iron boiler? There is so much grey area in hydronics... This seems pretty safe though!

salbertj

Thanks for the reply

Not sure what you mean by 3rd way on three way valve.Are you saying the mixed outlet?Also the pumps never shut down.Want to add a peerless partner but not sure how that would work with the mixing valve.I geuss it would not be able to be able to come off that header because of the mixed temps.Are there any good websites that illustrate these types of piping diagrams?TIA

J.C.A._3

3 way...

The 3 ports are ...supply, return and mix.Lets just throw another thought your way...there are also 4 way mixing valves. Supply, return, mix and by-pass.Let's talk about confusing NOW....

With a motorized valve, the temperature sensors are doing the job...through the control...and mixing the return water with the supply water, for a consistant tempurature to the system.

If there is a chance of "condensing teperatures" in the boiler , or the temperatures for maintaining the domestic hot water supply...the mixing valve will close, to make sure that either will be a "priority".Again..for some controls a mere function,but for others it becomes a priority,depending on the way they are programmed.

See where the professional comes into play here? I've been to the schools that taught me the differences and the proper use of their controls. Nothing makes me more mad than figuring out that I have the wrong control to do what I need when the screws hit the casing of a new install. Chris

John_82

pipe the tank before the mixing valve. The tekmar control may have priority built in... most of the boiler manufacturers have diagrams on their websites...

salbertj

Thanks for the reply.One of my many qeustions is with the pumps running constantly what keeps the heating zones from pulling hot water after the peerless partner has satisfied and the priority goes off?TIA