constant circ - Scott

ScottMP

I feel foolish asking this question since I should know the answer, but ..

With a constant circulating system using trvs, what controls the boiler ? Does it maintain temperature by a outdoor reset ? I know Viessman and Buderus have plenty of insulation for heat loss, but what about other boilers ? What controls do you guys use ??

Also if not using bypass's on panel radiators, would you use a monoflow ( scoop ) system ?


Scott " playing Dan " Milne

Online Sheriff \"Murph\"

nice hat

i think a pressure bypass valve would be in order

ScottMP

Yes

But what controls the boiler ??

As I said I have a small constant circ on my boiler but thats Buderus and it maintains as part of the ecomatic ( now logomatic ) set up. Just curious about other boilers.



To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

hr

At the ISH show this fall

Paul Pollets will be presenting a seminar on European Radiant methods. Should be a good lesson in constant circ and boiler reset. If you are in the Toronto area around late October, stop by.

hot rod

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Online Sheriff \"Murph\"

yeah outdoor reset

high,-low,-off

Online Sheriff \"Murph\"

is that with

injection pumping?if so a logic board to control the third and second pump.

ScottMP

HR

I want to go to ISH, but what do you do when you set up constant circ ??

Scott

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

ScottMP

It could be done with

Injection But WHAT CONTROLS THE TEMPERATURE OF THE BOILER !!!!

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

hr

With constant circ

as I see it you run the pumps all the time, so you pay a small price in electrical costs. I'm not that well versed in constant circ, Paul or others would be a better bet.

I know with tekmar reset controls (system and boiler) you end up with virtually constant circ if they are set up correctly. There are a lot of ways to "skin a cat" with pros and cons to each. Check em all out, there isn't just one right, or best way to install hydronics for every application. That is what keeps it so interesting and fun, I think. I'm always up for a new approch or technology.

hot rod

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Mark Hunt

Constant circ

Scott,

The last CS job that we did was on that panel job I posted pics of of few days ago.

We used a Taco OD reset control with a sensor strapped to the supply pipe. The control brings the boiler on at whatever temp you program it to and the boiler will then maintain the temp that the OD reset tells it to.

We used panel rads on that job and it worked out great.

Hope this helps!!!

Mark H

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Mark Hunt

Constant circ

Scott,

On the last constant circ job that we did, we used a Taco OD reset control to bring the boiler on and maintain the temp in the loop.

We strapped the sensor to the supply going to the system. We also used an OD stat to bring the pump on at the same temp as the boiler.

The reset then controls the temp going to the system and will shut the boiler down when the OD temp rises above the start setting.

The HS-2107 from Buderus is capable of doing this.

Hope this helps!!

Mark H

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

kevin

boiler control

Why could n't you use an HW 1824 or 1848? Set it up for pri/sec.and work off of that? just a suggestion for a guy who is new to this way of doing contoling... I am in the market to do this w/ my own house so I will be interaested in what comes of this disscussion.
Kevin C.

ScottMP

Yes mark it does

I just got to thinking that maintaining a temp was never a favorite of mine, so getting used to Buderus's way of maintaining was a jump for me. I get it know, but, was'nt sure how it works with ohter boilers. Your OD stat works like a warm weather shut-down, correct ?

Thanks for the help

Scott

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Bill NTSG

Out door reset

is the best way to control the boiler. Like you mentioned Viessmann and Buderus have the good controls. I have done a dozen Viessmann and 5 buderus this way. A less expensive option? Burnhams EC5000 . It is really a tekmar control. I have it on a few Burnham LE,Ledv's. It could also work on any boiler. Less expensive? Maintain temperature in the boiler with a 8124 but then you would need a 3 or 4 way mixing valve or injection pump with an indoor sensor to keep the place from overheating. Less expensive? How about a two stage t-stat. Maintain low limit in the boiler, first stage brings on pump, can't keep up ? ,second stage brings on burner. May not be constant but almost is better than not at all. Having lived with on/off t-stats and then having experienced constant circulation in my home I wouldn't want to go back to being without it.

Boilerpro

A limit on good application of outdoor reset in constant circ

Here's a very common problem I've found with outdoor reset. In structures where temps are set back when spaces are not in use, the recovery time is extremely long. The boost feature on Tekmar's controls is really helpful if thermostats are set up when boost is occurring. Also can wire in two stage stats to bypass the outdoor reset when necessary. What controls the boiler temp? Usually the injection control monitors boiler temp and fires the boiler only as needed, depending if you install the boiler sensor at the supply or the return and if the control is providing the reset or only set up for low temp boiler protection.

Boilerpro

Aidan (UK)

constant circulation

I think the answers are in John Siegenthaler's definitive article on outdoor reset control at PMEngineer. I had to print this article and read it a few times.

The two options are;
1) the boiler is controlled by the usual 180degF high-limit thermostat and the water is mixed to a lower temperature, using a mixing valve set or injection pumps, or

2) the outdoor reset control takes control of the burner and limits the boiler flow temperature to the lower value required by the outdoor reset setting. The boiler's 180 degF high-limit thermostat remains in place as a safety device, but shouldn't operate in normal operation.

http://www.pmengineer.com/pme/cda/articleinformation/features/bnp__features__item/0,2732,21624,00.html

Paul Pollets

Constant circ

Constant circ is regulated by the control, of course. In the Viessmann and Buderus controls, the pump(s) contantly circulate except in WWSD or DHW production, if priority mode is wanted. Most Tekmar controls also will also provide constant circ, and if I was in the office, I could give you the control #'s. The control is also monitoring the outdoor temps and boiler water temps, and possibly the indoor sensor (RTu) temp, to determine the correct water temperature needed. Low wattage pumps are used to extract efficiencies. In Europe, variable speed "smart pumps" are commonly used with the constant circ method to gain maximum system efficiencies.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Mike T., Swampeast MO

Temp \"Boost\"

That's where TRVs shine even more brightly.

If you set the reset temp 10-20 degrees above the requirement (depending on balance/type of radiation), you have a nice reservoir of heat when it comes time to raise the temp rapidly. As long as lines are reasonably insulated, there is very little energy waste.

Case in point: My DHW is from a stand-alone, natural gas, 110 gallon heater. Large old 2-story home with far-flung baths. I recently installed a gravity recirculation loop for DHW and carefully insulated the loop. I get hot water 3 times as fast in upstairs baths and can find no discernable increase in fuel use.

kf_2

Constant circ.

Scott,

Here is an answer. How about using a motorized 3 or 4-way valve that has an end switch to pull in the boiler when the valve is in the full open postion. Viessmann HK-1 Universal or a Tekmar #360 are some options.

hope this helps.
kf

Michael B

a few different options

Viessmann HK-1 is a nice 4 way with logic for constant cir. and outdoor reset for boilers other then Viessmann. Viessmann controls Vitotronic 200/300 do the trick on their own boilers (Vitogas 50/100 Vitola 200 etc.) Nice outdoor reset, constant circ. the works. Another manufacturer that has been drumming constant circ. into my head is Stadler. They have a nifty little Injection Mixing Station with high limit, 3 position actuator, and tekmar "advanced control for boiler reset, constant circ, and DHW control. All three products have done the trick for me.