Triangle tube not reaching setpoint

wrxz24

When baseboard zone and inslab radiant zones call for heat at same time during this cold snap in Vermont.



I think the boiler wont go to high fire due to the large delta T. Boiler protection?

Example-target is 156 supply 140 return 108

Inboiler pump is at speed 1. Piped prim/sec

Thanks in advance

R Mannino

Which Control?

Trimax or MCBA?? More than likely it's a setting in the control. Just my opinion. Move the pump to 2 and see what happens.

R Mannino

A Link to the Other Post

would help



http://www.heatinghelp.com/forum-thread/148010/Anticipator-setting-question



I see it's a Trimax, are you running one ODR curve or two??

wrxz24

I am running both curves

Yeah, sorry for not linking the other thread. Here is the original thread.

http://www.heatinghelp.com/forum-thread/147979/Delta-t





like I said, when the zones are running by themselves, the system works great. But when the high temp and low temp curves are calling at the same time, there is a huge delta T andvthe boiler will not fire at full speed. I think?

My mix valves are set at 120 for floor protection.



Thanks, Pete

wrxz24

The boiler is firing @100%

But the set point can not be reached when the high temp and low temp zones are calling.



Flame ionization is at 23. Not sure what that means.

R Mannino

Stupid Question

how is the house temperature?

wrxz24

House temp is o.k.

for now but my concern when the temps get much colder.  If the boiler can't reach set point now when temps are in the teens, the baseboard zones will not be able to heat the upstairs. 

I am thinking of buying a tstat with a slab sensor  like the tekmar 519 to see if keeping the slab at set point will improve the situation when the baseboard and slab zones call at the same time.



A cool slab gobbles up the btu's and my upstairs is paying for it. 

wrxz24

Still not reaching setpoint....

So this morning I went to check the boiler. It was running 100% high fire for the last few hrs. Floor temp is 81 degrees but the boiler still can not reach the set point on the higher temp curve.



I have only one baseboard zone upstairs and all 3 slab zones are calling downstairs. The mix valves are at 110. The setpoint temp is 162 and the boiler can only make 132 deg water.



Not sure what to do. I already throttled back the slab returns and it helped but my fear is that due to the low temp water mixing with the baseboard water, the boiler can not keep up....

kcopp

is the house warm?

and do you have enough hot water?

CMadatMe

Let's Take This Slow

Boiler Supply Water Temp = ?

Boiler Return Water Temp = ?



System Supply Water Temp = ?

System Return Water Temp = ?



Your piped pri/sec so you should have 4 different temps unless the secondary side flow rate has exceeded the boiler flow rate. If that is the case then Boiler Return Water Temp would Equal System Return Water Temp. What type of pump are you using as a system pump?

wrxz24

at the time

the house was warm enough.  I have the upstairs set at 64 when it was calling this morning.  The downstairs was 67 and tstat is set for 68.



The supply temp was at 132

The return was 98

The set point was 162

The mix valve is set for 110 for the  2 slabs in the house and 90 for the garage floor.

Floor temp was 81 according to the sensor

Outside temp was 8 degrees



I looked at the last few hrs and it showed that the boiler was on hire fire for about 3 hrs.



Each zone has taco 007 and the inboiler pump is grundfos 15/58 and is on speed 1.



My other thought is that maybe the garage floor heat came on and that is what caused the lower temps.  The tstat is set and 52.



In terms of getting system temps, do I get the temps for each zone before they mix at the manifold? 

wrxz24

system and bolier temps

the house was warm

enough.  I have the upstairs set at 64 when it was calling this

morning.  The downstairs was 67 and tstat is set for 68.







The supply temp was at 132



The return was 98



The set point was 162



The mix valve is set for 110 for the  2 slabs in the house and 90 for the garage floor.



Floor temp was 81 according to the sensor



Outside temp was 8 degrees







I looked at the last few hrs and it showed that the boiler was on hire fire for about 3 hrs.







Each zone has taco 007 and the inboiler pump is grundfos 15/58 and is on speed 1.







My other thought is that maybe the garage floor heat came on and that is what caused the lower temps.  The tstat is set and 52. 

















Reply

Edit

CMadatMe

Your Missing

Things here. You are piped pri/sec must the info below



Boiler Supply Temp =

Boiler Return Temp =



System Supply Temp =

System Return Temp =

wrxz24

bolier vs system temps

To get system temps, should I measure the supply and returns in each zone and also measure the temp of the water after the closely spaced tee's? 



The boiler return and supply are on the trimax control

Zman

Slabs

I think you understand that the underlying problem is the BTU hungry slabs pulling down the boiler. This really is not a problem unless it is causing the upstairs to underperform.

If it becomes a problem you could either control it "smart" with a system like Tekmar or you could throttle the slab circuits so they cannot take so much heat.

Carl

wrxz24

I understand the btu gobbling slab zones

But I thought if the slab was up to temp and stabilized, that the boiler would be able to get up to temp.



That is why I got the slab sensor, so the slab never got too cold. 





The upstairs is getting some heat but when the below 0 temps hit New England, I am not quite sure. 



To throttle the slab circuits, should I turn down both the hot and return valves to the mixing valve? along with the return line valve to the manifold  that I am already doing?  How would that affect the pumps to the slab? 

CMadatMe

No

I don't even want what the boiler is saying. I would like to know what the water temp is on the boiler supply entering the supply closely space tee and the boiler return back at the return closely spaced tee. Same goes for the system side. Water temps at the pri/sec point of boiler supply and return as well as system supply return.

wrxz24

I will get you that as

Soon as all the zones are calling. Probably tonight or in the morning. Right now the boiler is humming along st 11% with only the main slab calling.

SWEI

Setpoint

The supply temp was at 132



The return was 98



The set point was 162



If the house is comfortable, why are you trying to push 162ºF water into the slab?

wrxz24

The slab is not the problem

Its the baseboard zone that needs the 162 deg according to the outdoor reset. The slab has never been the problem. So if the upstairs is not getting enough heat, the boiler continues to run at 100% and never reaching the set point.

CMadatMe

Still Waiting

On the answer to my water temp questions. They are very important.

wrxz24

I will when all zones are calling it is supposed to

Get below zero tonight so I will get those for you. I love it when just the slab zones are calling. Low temps and a lot of condensation.



Right now I have 2 slab zones calling



Supply temp after tees -105

Return temp before tees- 73

Return tee- 88

Supply tee- 105

Zone 1 supply-105

Zone 1 return-83

Garage floor supply-90

Garage floor return-67



Not sure how long the garage floor zone has been running. The zone 1 floor temp is 79 degrees according to floor sensor reading.

wrxz24

Using an IR thermometer

Set point...166

Supply....150

Return.....115

Return T.....119

Supply T...150

Slab zone 1 supply....111.....return....91....floor temp 81

Slab zone 2 supply....105......return.....85

Garage supply....93....return....73

Baseboard zone supply.......150.....return......130





The outside temp is - 7.



The boiler has been firing at 100% for the last 5 or 6 hrs.



Edit...so I tried throttling back the inslab return water in all 3 zones by closing the valves until they were almost completely closed. The return temps in the boiler went up as did the supply temp. It was at 164 and return was 139. Not sure how doing that is going to affect the flow when just the slabs are calling....short cycle?

Zman

Good stuff!

The real question is.... What is the room temp on the baseboard zones?

The required water temp for those zones is not set in stone. The triangle tube curve is just a guess. The curve you require is based on the amount of radiation installed and the heat loss of the room.

Carl

wrxz24

Tstat is set at 64

I just went upstairs and the honeywell t87 was on the mark.



Zman, how does throttling the return valves from the slab zones to the manifold piping affect the flow to the boiler and then to the supply when just the slabs are calling? Will the boiler short cycle?

Zman

Throttle

Yes,

Reducing the amount of energy the slabs will take may increase the cycles.

It sounds to me that the baseboard zones do not need the energy the boiler is trying to send them. I would reduce the baseboard curves until they meet the buildings heat loss more closely.

Carl

CMadatMe

I'm really Confused

You stated that you were piped pri/sec. With the slabs only running you state that the boiler supply and system supply are the same temp. That would mean your slabs alone are taking just about the entire capable flow rate provided by the boiler pump. The reason I know is that your boiler return water temp is elevated by 5 degrees above your system return based on the temps you posted when just the slabs are calling.



You then posted the numbers when both the baseboard zone and slabs are calling. Your again posted that the boiler supply and system supply are the same temp. The boiler pump is a fixed speed pump. The boiler pump cannot just create more flow. If the system needs more flow you would be mixing return water temp with boiler temp at the pri/sec tees and that water temp would not be the same as the boiler supply temp and you are posting that it is.



I ran the math, that slab is taking 6gpm. The boiler pump on speed 1 only provides a 6.5gpm flow rate. So your only moving .5gpm to the baseboard? IF that is the case the bb output at 150 degree water is only about 360 btu/hr per ft.



(B Flow Rate) - (S Flow Rate)*B Temp + (S Return Flow Rate)*SysRtnTemp/B Flow Rate = Boiler Return Temp



(6.5 - 6) *105 + (6 * 73)/6.5 = 89



Are the radiant slabs the first zones and the baseboard the last?

wrxz24

I will play with the curve

To see if i can run lower temp water up there. In the mean time, if the weather is not so cold, I can adjust the shut off valves to increase the burn times when 1 or more slab zones are calling.

The only time the upstair zone calls for heat is when it starts to get real cold in the evenings. I also have a fairly large opening to the second floor so some heat from the slabs make it upstairs.

wrxz24

Yes, unfortunatley

The baseboard zone is last down the supply line. I have attached a drawing. I used an ir gun measuring temps on pipes wrapped with blue painters tape.



I also have throttled the flow from the radiant zones to the return manifold to assist in getting the boiler to reach its set point



When i took the first set of measurements, the baseboard zone was not calling.



So should i increase the inboiler pump speed?

CMadatMe

There's The Problem

Baseboard is on the last zone, slab is taking all the flow rate (ie, btu/hr) and the board zone is starving. Like I said 360 btu/hr per ft at that .5gpm flow rate - How many feet of board on that zone and is 360 x footage = btu/hr enough to get you to setpoint at design temp based on that zones heat loss?



Pull your triangle install manual page 82. On speed 2 the pump curve crosses the HX curve at at just about 9gpm.

wrxz24

I have 68 ft of baseboard upstairs

1 room is 18x18 with 20 ft of bb.

1 room is 16x 16 with 16 ft of bb

2 bathrooms with 3ft each

1 room is 12 x 14 with 10ft of bb

2 small areas 7x14 each that are around the balcony to the first floor each have 8ft of bb. 

So all in all about 1400 sqft of space including the 12x14 opening to the first floor.

The walls are 2x6 construction with blown in celluose. 

CMadatMe

Deleted Duplicate

CMadatMe

Guess

Its time to speed up that boiler pump. What the heat loss of each radiant zone and the baseboard zones?



Going back to your original post. Boiler supply 140 Return 108 - 32 Degree Delta-t



(Speed 1 Flow Rate is 6.5 or so x 32 x 500 = 104,000 btu/hr. Boiler Heating Capacity is 99,000 btu/hr. The 6.5 may be a little off, estimating off a graph.. I'd say the boiler is in high fire..

wrxz24

The two heat loss calculators,

One was 111,000, the other was about 90k,  so I went with something in between with the TT 110.



I will have to dig that up and do individual rooms. 

kayakingphotos

setback?

I'm no expert....



but are you setting back the temp at night? If you were, I could imagine that it would have issue coming back up to temp. And it also sounds like the baseboard and radiant zones have more ability to put out heat than what the boiler can create.



Chris, I don't recall the original poster saying which Triangle Tube boiler he had, but I did calculate that it was the one with the 99k DOE output....



Patrick

CMadatMe

Based On Other

Posts he has participated in its a PT110.

wrxz24

total heat loss is about 23k for the upstairs

The two bigger rooms have about 5,500k of heat loss with 20 ft of bb in each room

The 12x14 has about 4,600k of heat loss with 10 ft of bb

The two bathrooms have about 600 of heat loss with 3ft of bb in each

The two areas next to the opening to the downstairs have about 3,500k each of heat loss with 8 ft of bb in each.



Not sure how to factor in the 12x14 opening as I am gaining heat through that opening from the first floor slab zones.

wrxz24

I think kayak is right

It was -12 last night so obviously all zones needed heat. The boiler ran full tilt last night for 8 hrs with no dhw priority. I disabled priority it for the night. I wanted heat all the time due to the frigid temps. The boiler was able to produce 150 degree water with a 20deg delta t. I just do not think the boiler has the hp to heat the combined return temps of bb and inslab radiant.



I tried speeding up the boiler pump and that helped the delta t. I attempted to throttle the flow for the radiant returns and that helped. I haven't tried throttling the supply to the radiant zones, not sure how that will affect the pumps or the flow to the slabs? The manifolds have 10 deg delta t now.