Boiler suggestions
Last Post 09 Jul 2018 08:08 PM by Dana1. 9 Replies.
Printer Friendly
Sort:
PrevPrev NextNext
You are not authorized to post a reply.
Author Messages
CfrenchUser is Offline
New Member
New Member
Send Private Message
Posts:5

--
06 Jul 2018 03:42 AM
Hey everyone! Looking for some input/opinions. We are building a house, ICF to the rafters, 9ft ceiling no vaults and radiant slab (2520sqft single story ranch style,R60 attic and triple pane windows) My btu calculations came out to 63000BTU so I picked out a navien npe 240E to heat the house and domestic water. Our prints and specs went off the the energy code compliance which we have to meet for new builds here in Alberta and when they input the boiler it came up as possibly undersized. So now I am trying to decide between staying with the navien or switching to a viessmann 100W with a 300W indirect tank. Any input would be great appreciated! Thanks!
sailawayrbUser is Offline
Veteran Member
Veteran Member
Send Private Message
Posts:2270
Avatar

--
06 Jul 2018 02:05 PM
First off, if you have a good ACCA Manual J heat loss analysis, you can make a good decision on the size of the boiler. How comfortable are you that your 63,000 Btu/hour building design heat loss is accurate?
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
Dana1User is Offline
Senior Member
Senior Member
Send Private Message
Posts:6991

--
06 Jul 2018 03:15 PM
Posted By sailawayrb on 06 Jul 2018 02:05 PM
First off, if you have a good ACCA Manual J heat loss analysis, you can make a good decision on the size of the boiler. How comfortable are you that your 63,000 Btu/hour building design heat loss is accurate?


+1 on getting an AGGRESSIVE Manual-J (per the Manual's instructions) before picking the boiler.

For a 2530' ICF house with R60+ in the attic 63KBTU/hr would be the load with some windows open, or at an outside design temperature of -80F or something. (Even the colder locations in Alberta only have outside design temps in the -25F range: https://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf

With decent performance windows most houses like that would come in under 30 KBTU/hr @ 0F outdoors, 70F indoors, and still well under 40K @ -25F.

For reference, my 1923 vintage 2x4 antique 2400' house + 1600' of insulated basement w/ clear storm windows over antique single pane double-hungs comes in under 40KBTU/hr @ 0F, at about half the R values of an ICF house and crummier than code windows.

CfrenchUser is Offline
New Member
New Member
Send Private Message
Posts:5

--
06 Jul 2018 10:15 PM
I'm pretty confident now with the btu load needs. Did some discussing about the btu load with some good people.
Leaning towards a viessmann. I am now having trouble understanding how to properly incorporate the storage tank and have the boiler large enough to support both. I've had one person tell me I need a 200btu boiler for the water and then another tell me that a viessman vitoden 100 (125 btu) would be more than enough for our application.
2.5 bath, no fancy body sprays, one shower just has 2 shower heads. We would like to be able to have a shower while a dishwasher is running and maybe a sink.
sailawayrbUser is Offline
Veteran Member
Veteran Member
Send Private Message
Posts:2270
Avatar

--
07 Jul 2018 03:10 AM
I would guess your design heat loss to be closer to 40,000 Btu/hour then 63,000 Btu/hour. You can't just discuss this with people. You really need to run the numbers and first obtain an accurate design heat loss before you can begin thinking about boiler selection. I am sorry if you don't like this response, but anyone who tells your otherwise would be best to avoid.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
CfrenchUser is Offline
New Member
New Member
Send Private Message
Posts:5

--
07 Jul 2018 12:27 PM
Sorry I guess I should have specified who I talked with it was a certified hydronic specialist and my old boss who designs boiler systems now. I'm a plumber by trade but most my experience is in the commercial aspect of it. I won't take any offense to any suggestions. That is why I am on here
CfrenchUser is Offline
New Member
New Member
Send Private Message
Posts:5

--
07 Jul 2018 12:27 PM
Sorry I guess I should have specified who I talked with it was a certified hydronic specialist and my old boss who designs boiler systems now. I'm a plumber by trade but most my experience is in the commercial aspect of it. I won't take any offense to any suggestions. That is why I am on here
CfrenchUser is Offline
New Member
New Member
Send Private Message
Posts:5

--
07 Jul 2018 12:27 PM
Sorry I guess I should have specified who I talked with it was a certified hydronic specialist and my old boss who designs boiler systems now. I'm a plumber by trade but most my experience is in the commercial aspect of it. I won't take any offense to any suggestions. That is why I am on here
sailawayrbUser is Offline
Veteran Member
Veteran Member
Send Private Message
Posts:2270
Avatar

--
07 Jul 2018 02:39 PM
Anyone with zero credentials and zero experience can get “certified” by simply paying a fee to any number of alliances/associations. You would be far better off finding someone in your locality who is actually licensed and experienced and preferably a professional engineer...both for the heat loss analysis and for the hydronic radiant design. It will probably cost you way less and it will be way more likely to actually get done properly.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
Dana1User is Offline
Senior Member
Senior Member
Send Private Message
Posts:6991

--
09 Jul 2018 08:08 PM
Posted By sailawayrb on 07 Jul 2018 02:39 PM
Anyone with zero credentials and zero experience can get “certified” by simply paying a fee to any number of alliances/associations. You would be far better off finding someone in your locality who is actually licensed and experienced and preferably a professional engineer...both for the heat loss analysis and for the hydronic radiant design. It will probably cost you way less and it will be way more likely to actually get done properly.


Yup!

Even assuming for time being that the certified hydronic specialist is a competent at designing hydronic systems, that isn't the same skill set as calculating the load. It's possible to be competent at both.

So far we don't even know what indoor & outdoor design temps were being used for the load calculations, or whether they were appropriate for the location.

Find a registered P.E. selling Manual-J calculations as a service, pay the fee, get some real numbers.
You are not authorized to post a reply.

Active Forums 4.1
Membership Membership: Latest New User Latest: noooze New Today New Today: 1 New Yesterday New Yesterday: 0 User Count Overall: 34706
People Online People Online: Visitors Visitors: 117 Members Members: 1 Total Total: 118
Copyright 2011 by BuildCentral, Inc.   Terms Of Use  Privacy Statement