Tuning Indirect DHW Efficiency on TT Prestige Solo 110

margsuarez

Hello Heating Helpers,

I have a natural gas-fired Triangle Tube Prestige Solo 110 with outdoor reset and an 80-gal indirect hot water heater. We could probably do with smaller, but I didn't want to run out of water when filling our large soaking tub (bathtub filler wants 5gpm, 80gal). In practice I have found that keeping the tank at 114*F with a 4deg swing (6deg in summer) provides a comfortable supply of DHW. The setpoint is 140*F, and I have the anti-legionella function turned on.

Gas usage in summer is quite minimal (about .25CCF per day) but I think I can make it better. This morning I noticed a call for DHW. Storage temp read 110*F. When setpoint was reached, storage temp was about 112*F, supply was about 128*F and return about 124*F. I figure the boiler could just keep circulating until that 10*F difference circulating through the boiler was absorbed by the tank (post pump is set to 7min).

However, the boiler fired again, even though boiler temps were higher than storage temp and would probably be enough to satisfy the aquastat.

Any ideas of what else I can tweak to minimize # of firings needed to keep my storage tank at temperature? I have read some of the previous threads and I think I might be on track, but obviously missing something.

Thank you very much
marg

Zman

How is I piped? Does the dhw have it's own circ? What model indirect? Is there an anti scald mixing valve on the indirect?
With a setup like that, the boiler should run flat out until demand is satisfied.
Carl

Bob Bona_4

Tell us whether the indirect aquastat sensor is from TT and set up as such in the boiler control or is the sensor generic. Trimax or older control?

margsuarez

maybe some software thing is going on, like I'm hitting the 15dhw timeout? there's no space heating going on right now.

it's the trimax control. the control is configured to look at the aquastat sensor (I assume it shipped with boiler). is there a way to tell?

dhw has its own circ. (taco 0015 on low). internal boiler pump is wired to aux boiler and only comes on if DHW circ is not running (done with relay tail contact). indirect is Bradford white, can't remember the model but it is the basic type. there is no anti scald on the indirect (have to ask my plumber to put one) but storage temp doesn't really go higher than 140.

any thoughts? much appreciated.

marg

Robert O'Brien

If the boiler is showing the DHW temp on screen,it's set to use the TT DHW sensor. If you want to reduce cycling to the greatest possible extent, I would use a conventional aquastat set to 160 with a 45 degree differential. You need a mixing valve with this setup but you need one anyway. The tank would satisfy at 160 and not initiate a demand until the DHW temp fell to 115*
If the tank is oversized,you most likely will end up with one or no more than two cycles per day,and they will be long cycles!

Zman

I like the dhw sensor setup you have.
A 15 min timeout is too low.
In sensor mode, the dhw adder perimeter dictate the boiler target. The default is 46. If yours is set too low that could be the problem.

Try to watch the screen and see what is going on when it cycles.

njtommy

Sounds like the indirect tank is not picking up enough btus to keep you minimum firing rate. Also looking at your delta T it looks like its to low and your could be moving water through the indirect tank too fast.
too much flow/ gpm = low delta t.
low delta t = not enough but/ heat transfer.

njtommy

I would really like to know which tank they have and pictures of the install. This is not the first time Marg has posted question and pump problems in his system. I can only assume that he has problems with the install at this rate and pumps where just thrown in and flow rates and FT head where not considered.

margsuarez

Thanks for the ideas. I will post pictures when I get a chance. The tank is a Bradford White SW-2-80-L. I will experiment with settings and you know what I figure out. Increasing storage adder and circulator speed seems to have helped, but i still saw one 5-min fire, boiler setpoint (138) reached, then a 2-min fire to reach DHW setpoint. I think my boiler setpoint is too low, will play with that and see what I get. Will update in a few days (I only get to stare at this thing in the morning.

njtommy

What size piping do you have going to the Indirect tank from the boiler? Yes if your trying to store domestic hot water at 140 you need to bring your boiler temp higher then 140. I would set it at 160 if you can. Does your boiler have to heating set points?
Ie: Water supply temp for DHW and a separate water supply temp to heating?

margsuarez

it looks like 1" piping. i am storing at 114, and had max boiler setpoint at 140. I noticed that since increasing the max boiler setpoint (now 150) i no longer condense.

boiler does have separate config for space heating and dhw.

i am now playing with DHW call blocking; though i think the Fire-Setpoint Reached-Fire again cycle that I'm trying to prevent is for a single DHW call. so maybe that will have no effect.

Photos coming up.

thanks
marg

margsuarez

I think call blocking may be the ticket. according to the control supplement manual:

dHW call Blocking default: 0 Minute
DHW Call Blocking sets the minimum time between burner firings for domestic hot water calls. At the completion of a burner firing, the DHW Call Blocking time will begin. The burner will not fire again until after the DHW Call Blocking time has elapsed. The DHW Call Blocking time only prevents the burner from firing, the domestic hot water circulator will respond to a domestic hot water call. This blocking time has no affect on central heating calls. The DHW Call Blocking feature prevents short cycling of the burner and extends the life of the burner components.

too bad the controller isn't smart enough to see the temp differential and decide how long to block. I will let you know what i find...

margsuarez

Air handler and boiler. between the two are the CH1 Circ (grundfos alpha for AHU) and the CH2/SYS Circ (Taco 0015 for radiant floor).

margsuarez

near boiler piping. P/S with supplies on the left, boiler loop in center, and returns on the right.

to the left of the expansion tank you see the manifold feeding CH1 and CH2 pumps. (2nd photo)

to the right of the air scoop is the closely spaced tees to/from the boiler. (3rd photo)

head on in front of the boiler supply is the return manifold from CH1 and CH2 pumps.

DHW circ is another 0015 on low (high didn't seem to make a difference).

margsuarez

return manifold

margsuarez

CH1 and CH2 circs (pushing away)

margsuarez

AHU return and supply (L to R) coming from Alpha pump

margsuarez

Radiant manifold (CH2), HRV, and humidifier (mounted on AHU)

margsuarez

DHW piping

margsuarez

Here is the closest Boiler Piping diagram I found in the manual. It's Figure 9 on p. 21.

I don't have a Zone Panel, instead of zone circs, I have CH1 (AHU hydrocoil) and CH2/SYS (radiant manifold) circs wired to the TT controller. CH internal circ is wired to Aux Boiler, with a tail contact cutting off CH if DHW circ is pumping (Domestic Priority is turned on, so no space heating is happening).

From what I can tell it appears to be piped correctly... I do not have the pictured PRV bypass valve and I have an air scoop where they have the air separator.

margsuarez

OK, I just did the dishes then ran down to stare at the boiler. DHW call already in progress. It fired for at least 7 min then postpumped for 8. At the end of the postpump, Supply/Return/DHW were about the same, so all BTU's transferred with one ignition.

But it didn't condense. Getting close. Will tweak setpoint down a bit and see what happens.

Here are the current settings.

Boiler setpoint 140
DHW setpoint 114
DHW On Differential 10
Adder 26
Postpump 8 min
Priority Timeout 30 min
Priority Enabled
Call Blocking 7 min
DHW to CH Call Blocking 1 min
Anti-Legionella

Here's the data (sorry about the formatting). Attached is a graph.

Minute Mode DHW Supply Return
1 DHW Call 104 120 108
2 102 132 118
3 104 140 128
4 104 142 132
5 106 144 134
6 106 146 134
7 108 146 136
8 Setpoint Reached 110 146 138
9 114 136 134
10 Postpump 114 132 132
11 116 130 130
12 116 128 128
13 118 126 126
14 118 126 124
15 120 124 124
16 120 124 124
17 120 122 122
18 Standby 120 122 122

njtommy

The boiler will generally not condensate any time your return temp is above the 130 degrees. Lower returns temps are better, but for making DHW it's not uncommon.

I haven't look at the manual for this boiler yet, but I know minimal firing rate is roughly 25,000 btus. The more I think about that and your current set up. I think you need to store you hot water at a higher temp and have a larger offset. So maybe store hot water at 130-140 and have a 15-20 degree offset to keep the run times longer. Also when doing this you would have to add a mixing vavle on the out let of the tank so you don't get burnt.

As its running right now as u stated above you could be fine now, 8 mins is not a bad run cycle. As longer as the boiler doesn't refire again for DHW again.

margsuarez

An update - I was able to achieve acceptable performance by increasing "DHW Call Blocking" to 10 min. Since my boiler is a bit oversized (heat load is near the minimum range), this seems to do the trick.

Currently I am storing at 114 with a setpoint of 130 and an on differential of 8. The storage adder is 20.

Postpump of 8 min seems to dissipate most of the leftover heat in the boiler.

It is not condensing, but it is firing only once and the boiler temp and storage temp are very close when the cycle is finished.

I have anti-legionella turned on so once a week it should be bringing the tank to 140 although I have not yet witnessed this.

Thanks for all your suggestions.

marg

kolyan

I have the same boiler. According to manual DHW boiler setpoint is setting is not active when Sensor is used? Is that correct. What setting is actually responsible for hot water temp thats coming out of faucet? The Storage setpoint?

I had Switch aquastat on it, had temp set to 125 and it was comfortably warm. Now I have Sensor and even at 120F at storage hot water seems pretty hot

Zman

kolyan said:

I have the same boiler. According to manual DHW boiler setpoint is setting is not active when Sensor is used? Is that correct. What setting is actually responsible for hot water temp thats coming out of faucet? The Storage setpoint?

I had Switch aquastat on it, had temp set to 125 and it was comfortably warm. Now I have Sensor and even at 120F at storage hot water seems pretty hot

With the switch aquastat, you on off differential was established by the the default of the switch. Now that you are connected to the boiler you can (and should) adjust it.
As for why the temp is different now, it is probably a calibration or sensor depth issue. I would not get too concerned about it.
Modern boilers including the TT have tons of controls settings for DHW. If you have the will and patience to read the endless pages of the manual, you can dial in the temps and efficiency to your liking.

kolyan

kolyan

Those are my settings. I only changed Storage setpoint to 120F. 
I am an electrician, no a plumber. I do know a little about this stuff and I did read manual but still not very clear 

margsuarez

Not sure if this is your issue, but the Anti-Legionella function will bring the temperature of the tank to 140 periodically to kill germs. This caused some uncomfortable temperatures at the tap. For this reason I had a thermostatic mixing valve installed (Thanks Paul S.!) and haven't had to worry about the DHW since.

kolyan

I have thermostatic mixing valve installed and boiler reads storage temps in 120s. 

As I understand, in Switch mode boiler send DHW boiler setpoint temp (i had 186F default) to tank and stored it at aquastat temp (125 in my case, unless it was broken). Which setting is responsible for sending temperature in Sensor mode? In manual i think it says storage temp + adder is the boiler setpoint and thats the sending temp? 

I called support. But tech is a weird guy....not very happy about me calling 

unclejohn

Thats because your not supposed to be goofing with those parameters. The TT tech guys are really good. And they are used to talking to people who service boilers for a living. That said if you have a mixing valve set your tank temp to 140*F And stop crying over a few cents because you are going to shorten the life of your boiler by having so many cycles per DHW call. There is no way you can heat your tank and condense the entire cycle, unless you have a 3min cycle. 40 or 50 3 min cycles.

Zman

I believe it is the adder temp. You can turn that down until the boiler cycles or the indirect does not keep up.
I would just goof with the settings until you get results you like.

kolyan

unclejohn said:

Thats because your not supposed to be goofing with those parameters. The TT tech guys are really good. And they are used to talking to people who service boilers for a living. That said if you have a mixing valve set your tank temp to 140*F And stop crying over a few cents because you are going to shorten the life of your boiler by having so many cycles per DHW call. There is no way you can heat your tank and condense the entire cycle, unless you have a 3min cycle. 40 or 50 3 min cycles.

I somewhat agree, but as a home owner I would like to know how to tune the settings otherwise whats the point of having them in the first place. I tune in all my settings on everything. Its not like I am some soccer mom playing with this stuff, I connect those boiler for a living and others, I am just not a plumber to know all those details.
The pro who installed the boiler didn't even bother to move outdoor reset away from sun. Most people just don't care about this stuff as long as boiler works. I like everything tweaked and run as efficient as possible, and yes I don't want short cycling as well

Installed weil mclain few weeks ago and plumber had no clue how to set it up. I had to call tech support and find out. They were a bit more helpful than TT guys, walked me through all settings etc 

mattmia2

It really is in their best interest to tell anyone that will listen how to properly configure their product.

unclejohn

I don't mind being beat up on things but here is the warning in the TT installation guide.
" Qualified installer:
Prior to installing this product read all instructions included in this manual and all accompanying manuals/documents with this appliance. Perform all installation steps required in the proper order given. Failure to adhere to the guide-lines within these manuals can result in sever personal injury, death or substantial property damage.
Homeowner:
This product should be maintained / serviced and inspected annually by a qualified service technician. This manual is intended for use by a qualified Installer/Service Technician.

On my reply to @kolyan I thought he was the original poster who really has no business in the parameter settings. So now @kolyan say's he installs boilers but calls a plumber to set it up?
The installer does the setup. Also it's my guess that your WM was a CI and not a lot to set up. So instead of bad mouthing TT reps go to their two day school and learn how to properly set up and install the product your selling. Same for WM. Personally I tell my customers to call me and I will be happy to return for no charge and tweak the boiler after its been in a while. Rather then have them goof with it.

kolyan

unclejohn said:

I don't mind being beat up on things but here is the warning in the TT installation guide. " Qualified installer: Prior to installing this product read all instructions included in this manual and all accompanying manuals/documents with this appliance. Perform all installation steps required in the proper order given. Failure to adhere to the guide-lines within these manuals can result in sever personal injury, death or substantial property damage. Homeowner: This product should be maintained / serviced and inspected annually by a qualified service technician. This manual is intended for use by a qualified Installer/Service Technician. On my reply to @kolyan I thought he was the original poster who really has no business in the parameter settings. So now @kolyan say's he installs boilers but calls a plumber to set it up? The installer does the setup. Also it's my guess that your WM was a CI and not a lot to set up. So instead of bad mouthing TT reps go to their two day school and learn how to properly set up and install the product your selling. Same for WM. Personally I tell my customers to call me and I will be happy to return for no charge and tweak the boiler after its been in a while. Rather then have them goof with it.

Thats not what I said, you got everything wrong....I am not a plumber and I don't sell boilers. I am an electrician and I wire them. On the last job I had to set up Weil Mclain because plumber didn't know how to do it. And I had to fix wiring on mine at home because previoius "professionals" who installed TT did it wrong

As a homeowner, I just want to know a few settings. Its pretty stupid to call "professional" who might not even know anything, just to adjust my water temp etc. This isn't really a rocket science here. It would probably take me 5 minutes to learn all menu parameters and know them better them most plumbers. 
As far as servicing my unit, I did call plumber to do it just last month. I just didn't bother asking if he knows all parameters or not. And he obviously didn't care if they are setup correctly. Only later I noticed that I needed to replace a few sensors and that's when I decided to adjust some setting.

kolyan

Ps. I am not bad mouthing tt reps. I just said they weren't very helpful and wanted to explain everything. Unlike weil mclain reps who were a pleasure to deal with. I probably made a mistake and called as a homeowner and should have said that am I an electrician instead.

I have everything figured out pretty much. The only thing that I don't get is Pump Post Time for heat and hot water. I understand what it does, I don't understand why 1min is default value on mine and 5min default on pretty much the same boiler from TT (according to manuals). And why range is from 0 to 30. If this setting maximizes the efficiency of boiler according to manual, is there a reason it should be at 1 min instead of say 5 min?

mattmia2

The longer the post purge, the more overshoot you get in the setpoint of the tank. If there is a thermostatic valve on the outlet that regulates the temp it isn't that big a deal, if there isn't you can get a wide fluctuation in dhw temp with a long post run time. It will also have to suppress a dh call or essentially run both a dhw and dh call at the same time if there is a dh call when the dhw call is satisfied in which case you are dumping heat in to the tank that could be satisfying the dh call unless it has logic to suppress the purge if there is another active call.

Zman

It is good idea to have some post purge. It let's the heat exchanger in the boiler cool off a bit after the burner turns off. I have seen boilers trip their high limits when the PP is set too low. Some folks like to run it longer to pull more heat out of the boiler.
The manufactures default will usually be pretty close to what is needed.
Based on the (good) questions you are asking, I think you are more qualified than most installers I run into. All boiler manuals have stern language about qualified installers, most installers I see are anything but...

ednelson7373

my name is Ed I am in tech support with Triangle Tube and we would be happy to discuss any concerns you are having you can reach us 8-5 eastern time Monday through Thursday and 8 -4:30 at 856 228 8881
thank you
Ed

kolyan

Thanks everyone. I'll try to give TT a call again if I have more questions. Been busy lately with work and family 

kolyan

I guess I do have another question. So the default values for DHW setpoint on most boilers is set at 180-186F with storage temps at 140F. Does it make sense to lower the DHW boiler setpoint? Especially if storage temperature is lowered as well to 120F