Joined on December 29, 2008
Last Post on February 25, 2014
@ December 16, 2013 2:10 PM in 6 Heaters - need one programmmable controlI'm very surprised. Where are you located?
@ December 16, 2013 1:43 PM in 6 Heaters - need one programmmable controlIf you ask them who the local rep is they will give you their number. I'm sure the local rep will give you a qualified contractor in your market.
@ December 15, 2013 8:22 AM in What is the most effective way to handle a MODCONAll the buffer is really doing is allowing the full boiler flow rate a place to go no matter the modulation rate. The pump is fixed speed. If you had a variable speed pump being controlled by the boilers control logic to match the modulation rate based on the systems demand that issue goes away and there would not be a need for the buffer tank.
@ December 15, 2013 8:00 AM in What is the most effective way to handle a MODCONHere in the great USA. Fixed speed boiler pumps. They are the main cause of short cycling most of the time, the reason for elevated stack temps and high boiler return water temps when zoning.
Get variable speed boiler pumps controlled by the boilers logic to match its flow with the modulation rate of the boiler and they go away. The attached chart is provided by one mfg as the modulation rate in comparison to efficiency in its boiler. I don't know anyone else that publishes this.
@ December 14, 2013 3:51 PM in Triangle tube not reaching setpointPosts he has participated in its a PT110.
@ December 14, 2013 3:29 PM in Triangle tube not reaching setpointIts 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..
@ December 14, 2013 11:14 AM in Triangle tube not reaching setpointBaseboard 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.
@ December 14, 2013 8:44 AM in Triangle tube not reaching setpointYou 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?
@ December 13, 2013 5:51 PM in Friday the 13th Boiler FailureIs the better choice. Down to like 12 input.. Viessmann has a program for displays. Rather nice one.
@ December 13, 2013 5:48 PM in Triangle tube not reaching setpointOn the answer to my water temp questions. They are very important.
@ December 13, 2013 3:35 PM in Low-Loss Header: am I understanding this correctly?Just have this boiler installed? Suggest you speak with your installing contractor. To answer your question. The boiler pump speed 2 and don't know what your gpm and head requirements are for the system side so can't tell you what speed to put the system pump at.
@ December 13, 2013 3:31 PM in Friday the 13th Boiler FailureA new 200? Turn down is way lower..
@ December 13, 2013 11:34 AM in 6 Heaters - need one programmmable controlSimple out of the box stuff and can do it all from your office computer
@ December 13, 2013 8:36 AM in Low-Loss Header: am I understanding this correctly?You can run the boiler on a different delta-t then the system and in Viessmann's case you must since the max flow rate across the HX on the Vitodens 100 and 200's -19/26/28/35 is 6.2gpm
In the boiler control when you scroll the information via "I" button - Common Supply Temp is your low loss header temp.
@ December 12, 2013 3:34 PM in Triangle tube not reaching setpointI 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.
@ December 12, 2013 3:32 PM in Variable Speed Pump with a low head loss systemTo pipe with a low loss header. Could have piped direct. Since you did, best option for a system pump is a B&G Vario.
@ December 12, 2013 10:26 AM in Triangle tube not reaching setpointThings here. You are piped pri/sec must the info below
Boiler Supply Temp =
Boiler Return Temp =
System Supply Temp =
System Return Temp =
@ December 12, 2013 9:01 AM in Triangle tube not reaching setpointBoiler 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?
@ December 9, 2013 6:30 PM in Navien ch 240Of the home have to do with it. The question is, What is the hot water demand and what is the heat loss of the home. You know better HO1..
@ December 6, 2013 1:23 PM in Gas Conversion Help.Tim, agree with you but times are different. It also falls in with the PVC venting debate. Kind of the same thing isn't it?