TT Prestige 110 pump wiring question

masterofnone

I installed the Prestige 110 and entire radiant subfloor system in 2010. It provides our domestic hot water also with a Smart tank. Our home is a 1600 sq. ft ranch with full basement, two zones on first floor and one zone through basement. Each zone has it's own Grundfos 3 speed UPS 15-58 pump. Initially, the Prestige short cycled unless outdoor temps were very cold. Adding a large cast iron radiator to the basement zone served as a heat sink and the Prestige behaved nicely thereafter but... I also began running everything from one centrally located thermostat. The system has worked flawlessly, but I'm wasting electricity by running all three pumps whenever there is a call for heat. I want the basement zone circulator to be on whenever there is a call for heat at either upper zone. I'm utilizing a Taco SR504 Switching relay but not sure there's a way to wire it such that one circulator is always on whenever EITHER of the other two circulators are on. Just trying to save electricity by running only two pumps when needed. I'm thinking of tapping into the 120 volt leads to the Prestige's internal CH circulator to power the basement zone circulator. Would anyone familiar with the Prestige see an issue with doing that? Unless there's a way to wire the Taco relay for this unusual application. A situation brought on by a homeowner installation, I realize.

Thank you.

Gordan

Aren't you concerned about the basement zone overheating?

The short answer is yes, as long as the circulators add up to less than 2A (I think; check the install manual) - and the usual 1/25 hp ones will - you can connect them to the terminals on the Prestige.



But if you're going to do this, and you're using your basement rad as a buffer of sorts, why wouldn't you just pipe it as part of the boiler loop so that the boiler circ circulates through it? You'd want to repipe with appropriately sized pipe in order to ensure adequate flow, but if eliminating circulator power usage is your goal and you have a good reason to not care about the comfort and energy consequences of always sending heat to the basement, then this would be the way.

masterofnone

cool basement

The full basement is unfinished and is still a bit chilly in winter (that's fine). There are few basement emitters other than the CI radiator. I'm trying to avoid re-piping at this time( $$$) , just thought it best to avoid running three pumps when not all three are needed. You are correct, Gordon...the manual does state that maximum circulator continuous current draw is 2 amps per circulator. So then, I shouldn't be presenting any issues by splicing the basement zone pump into the CH circulator leads from terminals 1,2,and 3? The CH circulator is set to medium speed. The zone circulators run at less than high speed.

I did contact Taco about the application utilizing the SR504. They were unable to offer a good resolution.

Thanks again.

Alan (California Radiant) Forbes

SR504

There are never enough end switches.  Taco should supply an easy way to add on end switches, but until then, adding the basement circulator to the CH Solo wiring shouldn't be a problem.

masterofnone

I'll give it a whirl

Thanks for your replies. An available end switch on the Taco switching relay would have been nice. The isolated end switch on the SR504 connects with the T-T terminals on the Prestige. I'll try to make the changes this weekend and comment if any issues arise.

I want to add that I have been extremely satisfied with the reliability and performance of the Triangle Tube Prestige N.G. boiler. It's not a common boiler in our area but... I have a heating contractor perform some annual maintenance and emissions testing. They are impressed with the design.

SWEI

Is the outdoor temperature sensor installed

...in an appropriate location and the ODR curve properly set?  I've seen an unfortunate number of these "installed" without bothering to do so.

Jean-David Beyer

I've seen an unfortunate number of these ...

My former contractor did not want to install the outdoor sensor (even though it came "free" with the new boiler). I insisted he do so, but he said they did not make much difference. Since he recommended a greatly oversized mod-con,  I assume they made no difference because they ran at the lowest firing rate the boiler could manage on design day, and rapid cycled the rest of the time.



So I insisted on the smallest boiler in the product line. He then left the reset curve at the default setting that was way too hot. I fixed it myself.

masterofnone

Glad you asked

The system has been running without outdoor reset installed, unfortunately. From reading posts here for some time I knew it was best to utilize it. Perhaps another aspect of a homeowner install... settling for a boiler working, when it could be working at higher efficiency also... at least I hope. Yesterday I mounted the outdoor sensor on the north end of our house up near the overhanging eave. I chose the location to avoid direct sunlight and heavy rain. I tried to follow the Triangle Tube manual recommendations. There was no maximum wiring length specified. The distance required from boiler to sensor is about 70 feet avoiding all house wiring as much as possible. Should that wire length create any issues? It's 18 gauge wire. The sensor should be able to handle some rain I would think.? It would be nice if wind chill could be accounted for. Our home sits in a brutally cold location with high winds off one of the Finger Lakes of central N.Y. through much of the winter.

I remember seeing good previous posts here concerning ODR and tweaking the curve. I'll search them out before asking questions. I may connect the sensor wires in the morning. Nights are getting into the forties. Any recommendations are appreciated.

SWEI

Don't change anything else

Until you have that sensor working. 70' of wire is not an issue at all.  Take the winter to tinker with your reset curve - when you get it set right, pumps will be running nearly 24 hours a day.



Then it's time to take a look at your pumping costs and decide if it's worth modernizing there.

masterofnone

Internal CH pump speed and ODR hi limit effect?

ODR is hooked up. I'd appreciate recommendations regarding the Prestige's internal circulator speed setting. Specifically I'd like to know whether running it on low speed would provide adequate flow through the boiler. I realize there are factors to take into consideration. All near boiler piping (1") is according to the TT manual with Primary Secondary. Three radiant zones each use their own 3 speed Grundfos circulator and manifolds to monitor flow. Loop lengths are within spec using predominantly subfloor pex in plates. The 110 boiler is oversized for our heat loss of 70K BTU, but it supplies a Smart 40 gal. indirect tank also. I ask about reducing the internal pump speed because the boiler cycles slightly more than I prefer in the fringe season (currently 40's) if not all zones are calling for heat. I thought that a low internal pump speed would permit the secondary zone pumps to pull the heat from the boiler to reduce short cycling. I'd rather not increase the secondary pump speeds in order to preserve electricity costs. My biggest concern is harming the boiler or reducing it's longevity.

One more factor. Previously without ODR enabled the boiler's hi temp setpoint was 140* for condensing. It's kept our home warm for two winters. I only increased the hi temp limit to 150* after hooking up ODR. Factory default is 186*. Would changing to the higher setting have any impact on boiler cycling? Thanks