Power venting question!

raserion

Hi everyone.

I am replacing a 30 gallon electric water heater that's on its last legs with a 50 gallon natural gas one, the chimney is gone and the chase blocked.

Is it is better to have my gas furnace and water heater (both are natural draft) have their own power vent/flue or can they share one provided that I get the correct control kits and ensure the power vent and flue are capable of handling the combined BTU output? I live in Massachusetts by the way. Your feedback would be greatly appreciated!

I'm looking at getting one Tjernlund HS1 power vent (includes UC1 control board), a WHKE millivolt interlock kit for water heater, and a MAC1E multiple appliance interlock kit. This will supposedly let me vent both the furnace and water heater with one power vent and flue.

Steamhead

The problem with any power-venting system is its mechanical complexity. All those added moving parts will require service as long as they are installed, and when they fail they will keep the units from operating.

We have several customers with these units. In each case either the present or a previous owner took the el-cheapo way out of a chimney that needed repair. Then we get the no-heat call on a ten-degree night and find the power venter broke down.

I'd fix the chimney. When this is done, you will have a venting system that uses no moving parts, and should last as long as we do.

raserion

Hi Steamhead, thanks for your quick reply! I definitely wouldn't like to be in that situation. However what if I were to say the chimney is already gone and the floors closed up and power venting is the only way?

Steamhead

Then you should have posted this before killing the chimney.

It sounds to me like you have gotten yourself into a corner. Do you have a safe place to vent that setup that will meet Code in your area? Typical Code provisions might dictate that the venting point must be:

12" above the maximum recorded snow accumulation in your area;

Four feet from any wall penetration, such as a door, window, exhaust fan etc.;

Four feet from an inside wall corner;

Seven feet above a public or publicly accessible walkway;

etc. etc. etc.

These are safety-related issues. If you do not have a suitable location for a power vent, as a professional I cannot tell you that your proposed solution will work.

j a_2

Refer to NFPA54 2012. As well as the manf instructions prior to investing any of ur hard earned monies...manuals are supplied by the manf. And hard copies of the gas manual are available here in Braintree MA. We have had some recent changes, that were passed on in our recurrent training... I advise to move with caution on this one....

Bob Bona_4

If clearances are met, 2 appliances on one pv are typical. Being gas fueled, the pv stands a better life expectancy than oil. Tjerlund is the hardier make IMO.

Down the road it may come to be that you will switch to a direct vent 90 plus furnace and a wall hung tank less WH, then the pv would be obsolete.

j a_2

what is the manufacturer and model number of your water heater

raserion

I had a spot that satisfies those requirements except the 12" inches above maximum recorded snow which is would be ridiculously high after this last winter.

j a said:

Refer to NFPA54 2012. As well as the manf instructions prior to investing any of ur hard earned monies...manuals are supplied by the manf. And hard copies of the gas manual are available here in Braintree MA. We have had some recent changes, that were passed on in our recurrent training... I advise to move with caution on this one....

Thanks, I'll check it out.

raserion

j a said:

what is the manufacturer and model number of your water heater

I have a Rheem Performance Plus atmospheric 50 gallon, natual gas, model number# XG50T09HE40O

j a_2

I can tell u this that the way the water heater came out of the factory is how it has to be vented.. They do not support any aftermarket modifications....I was a long time service provider for Rheem. Here in Mass, and I repeat Mass if its not approved by the manf. Its not allowed,..In some cases you have the right to appeal...This is the best I can tell you based on the information I have...Anything is possible and I am definitely not the final say....But when I saw ur post a red flag went off in my head....

SWEI

Was this planned as a sidewall vent?

If the chimney is gone, do you at least have room to install some B-vent (or perhaps even PP venting for a higher efficiency unit)?

raserion

Yes, the chimney was removed because we planned on replacing it with a power vent and yes we are going to be using B-vents.

According to 2015 NFPA 54 12.4.3, I can install a mechanical draft system unless I am missing something.

j a_2

If the model # you posted is a natural draff. I encourage you to call Rheem tech...Hope it works out....Best of luck

Bob Bona_4

Good idea ja. As far as I knew, Fields or Tjerlund provides the draft, dialed in, so the appliance doesn't know or care if it's hooked to a chimney or it's mechanically drafted. And of course the usual interlocks and prover controls accompany the install.

Rheem's got a different directive? Wouldn't hurt to check.

j a_2

Definity a good idea...I am giving you my OPINION...Based on prior experience...Codes and rules change constinaly...its near impossible to state facts here....on such a situation. Good luck

Steamhead

Are you certain that your jurisdiction uses NFPA 54, rather than some other Code like the International Fuel Gas Code?

And are you certain your jurisdiction has not added some of their own requirements to the basic Code, as Baltimore has done?

j a_2

Yes certain. Why?

j a_2

As a master plumber,and installing gas appliances since 1979 here in Mass... I best know the code we are required to follow

Steamhead

Here are some more tidbits from the 2006 edition of NFPA 54. This is the newest edition I could find quickly online where everyone can read it, here:

https://ia701201.us.archive.org/9/items/gov.law.nfpa.54.2006/nfpa.54.2006.pdf

(Begin quote)

12.9.1 A mechanical draft venting system shall terminate at
least 3 ft (0.9 m) above any forced air inlet located within 10 ft
(3 m).

12.9.2 A mechanical draft venting system of other than
direct-vent type shall terminate at least 4 ft (1.2 m) below, 4 ft
(1.2 m) horizontally from, or 1 ft (300 mm) above any door,
operable window, or gravity air inlet into any building. The
bottom of the vent terminal shall be located at least 12 in.
(300 mm) above grade.

(End quote. They don't mention snow-line clearance or distance from adjacent buildings in this section. These may be typically local requirements, but we do run into them.)

(Begin quote)

12.9.4 Through-the-wall vents for Category II and Category IV
appliances and noncategorized condensing appliances shall not
terminate over public walkways or over an area where condensate or vapor could create a nuisance or hazard or could be detrimental to the operation of regulators, relief valves, or other equipment. Where local experience indicates that condensate is a problem with Category I and Category III appliances, this provision shall also apply.

(End quote- boldface mine)

Then you have the issue of clearances to combustible material, which are typically 6-9 inches. These were in a table which I couldn't copy and paste here.

Going through a combustible exterior wall?

(Begin quote)

12.11.14.2 A vent connector made of a single-wall metal pipe shall not pass through a combustible exterior wall unless guarded at the point of passage by a ventilated metal thimble not smaller than the following:
(1) For listed appliances with draft hoods and appliances listed for use with Type B gas vents, the thimble shall be a minimum of 4 in. (100 mm) larger in diameter than the vent connector. Where there is a run of not less than 6 ft (1.8 m) of vent connector in the opening between the draft hood outlet and the thimble, the thimble shall be a minimum of 2 in. (50 mm) larger in diameter than the vent connector.
(2) For unlisted appliances having draft hoods, the thimble shall be a minimum of 6 in. (150 mm) larger in diameter than the vent connector.
(3) For residential and low-heat appliances, the thimble shall be a minimum of 12 in. (300 mm) larger in diameter than the vent connector.
Exception: In lieu of thimble protection, all combustible material in the wall shall be removed from the vent connector a sufficient distance to provide the specified clearance from such vent connector to combustible material. Any material used to close up such opening shall be noncombustible.

(End quote)

See how complicated it can get?

I say again, you would have done better to post here before removing the chimney.

j a_2

Lot of good information there...But the bottom line,is that model number, if posted correctly code approved to be power vented? Secondly did you find out if we in Mass have a new code?

j a_2

The poster stated he was from Mass..and NFPA 2006 is not our code

Steamhead

I used that one because it was available online. 2015 might have some differences, but I could not find it to link to. If you can provide such a link, please do.

Besides, I'm sure there are other jurisdictions still using 2006, and people from those areas will probably read this. And we haven't even addressed the International code that some areas use.

raserion

The screenshot I posted with highlighted portions in my previous post was taken from NFPA 2015.

Yes I called Rheem. The water heater must be installed with the factory draft hood, aside from that there are no restrictions (aside from regular restrictions).

raserion

I now intend to use a Tjernlund HS1 power venter/control kit for the furnace (I already have a mechanical draft regulator installed by the previous owner) and a Tjerlund VP-2F (http://www.tjernlund.com/Tjernlund_VP-2F_VP-3F_8500567.pdf) for the water heater. Supposedly it will outlast the water heater that I bought which, if true, is good enough for me.

I have an open crawl space in the basement so I think it should be enough air for both appliances.

raserion

j a said:

The poster stated he was from Mass..and NFPA 2006 is not our code

Yup, I'm in Massachusetts. Did a bit more research and it seems that we use 780 CMR 68.00. Specifically 6801.5

j a_2

Steamhead said:

Are you certain that your jurisdiction uses NFPA 54, rather than some other Code like the International Fuel Gas Code?

And are you certain your jurisdiction has not added some of their own requirements to the basic Code, as Baltimore has done?

We in Mass are required by law to attend recurrent training yearly, we are required to carry with us the state plumbing and fuel gas code book, as well as as of now NFPA 54 2012, and prior to installing any fixture or appliance it must be listed on the Mass state plumbing board web site…If its not you have the option to file an appeal…Normally that don’t go well…..I attend state plumbing board meetings, as I find them very interesting and a world ok knowledge…When I was a teacher for a few years at Quincy high school on a part time basis, I took my plumbing and heating students there on a field trip…Today I am pleased to see that many of them are now fine young men and lic plumbers, here in Mass…In fact one of my former students , and former combat Marine is assusming my business…I would assume you in Baltimore have similar requirements, don’t you?

Steamhead

The short answer is "it depends". In Maryland, Code adoption and enforcement takes place on the local, rather than the state level.

For example:

Baltimore City uses the 2012 International Fuel Gas Code, with modifications as outlined here. This a pretty long .pdf, go to page 153:

http://archive.baltimorecity.gov/portals/0/charter and Codes/code/Art 00 - Bldg, Fire.pdf

Other Codes adopted in Baltimore City are all international codes, with the exception of the National Electrical Code (NFPA 70).

Neighboring Baltimore County uses a mix of International and NFPA Codes, again with modifications:

http://www.baltimorecountymd.gov/Agencies/permits/pdmbldgplansrev/firecodes120705.html

The Washington Suburban Sanitary Commission has its own plumbing and gas Codes:

https://www.wsscwater.com/files/live/sites/wssc/files/PDFs 6/2013CodeFINALE-Version.pdf

And every jurisdiction has its own licensing.

RobG

Steamhead said:

The short answer is "it depends". In Maryland, Code adoption and enforcement takes place on the local, rather than the state level.

For example:

Baltimore City uses the 2012 International Fuel Gas Code, with modifications as outlined here. This a pretty long .pdf, go to page 153:

http://archive.baltimorecity.gov/portals/0/charter and Codes/code/Art 00 - Bldg, Fire.pdf

Other Codes adopted in Baltimore City are all international codes, with the exception of the National Electrical Code (NFPA 70).

Neighboring Baltimore County uses a mix of International and NFPA Codes, again with modifications:

http://www.baltimorecountymd.gov/Agencies/permits/pdmbldgplansrev/firecodes120705.html

The Washington Suburban Sanitary Commission has its own plumbing and gas Codes:

https://www.wsscwater.com/files/live/sites/wssc/files/PDFs 6/2013CodeFINALE-Version.pdf

And every jurisdiction has its own licensing.

Sounds just like Virginia.

j a_2

Kinda thats why i mentioned the other day that major code issues are not very helpful here on this site…Way to many variables…General questions are fine….Theory doest change from place to place, codes rules and laws do...

raserion

Update: I'm returning the natural draft Rheem and getting a smaller capacity power vented model. It's about $350 more but makes things easier. There still is the question of venting my furnace though.

Jack

I just came onto this thread and I want to say that I think your original plan was correct. That Tjernlund or its Field equivalent (I'm partial to Tern, but we must be fair) would have allowed you to vent both appliances. You could have kept the simpler water heater and when that water heater went you could have replaced it with a simple tank. Now, with the lower capacity DV unit you get to replace the whole thing when it fails. A power venter system is reliable when cleaned/serviced. If the fan is allowed to get crapped up, then you have problems.

I would suggest that the entire system should have been evaluated. There is no natural draft system and yet you have (had) natural draft appliances. I think you would have been better off with a tankless water heater, but that horse has left the gate. Before spending on making the natural draft furnace operate I would suggest that you consider replacing it with a 90+ % efficiency appliance that would also be dv.

You will be able to make the current furnace work, but I think you are throwing good money after bad. How old is it?

j a_2

When you do return your natural draft water heater, just make sure you are able to meet all the requirements on the install instructions…What comes to my head is length of vent, height off the top of the water heater and termination requirements…As well as make up air and gas pipe sizing…All the years I served as a service provider for Rheem/Rudd/GE, It was often difficult to tell the homeowner , and yes , some plumbers the install did not meet the requirements and I refused to provide warranty work…What happened then is I would have to fill out my dispatch report and fax it back…Warranty void…Proceed with caution,and you will be fine..

j a_2

Wondering how you made out? Let us know if you need more help