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Joined on March 1, 2007

Last Post on July 28, 2014

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@ October 16, 2012 3:24 PM in Power vent condensation problems

Do you think an oversized furnace short-cycling like crazy is a part of the problem? I would look down on the HX right away. It will not last with the current condition. As proposed, Double wall vent connector is always a good idea. Your double wall pipe is hitting the exhaust gases with whatever temps are outside pushing the stack temps below dew-point temps. Disconnect the cold air intake side for a while, making sure your set-up is correct and I'll bet things will improve. As noted, this is an attempt to create a kinda/sorta direct vent system with a single wall penetration. I'm thinking you are going to have short life from this furnace HX.

You understand the combi question perfectly

@ October 16, 2012 3:10 PM in Rinnai Advice DHW Combi

And your outputs are correct for the 75/110. I will say that I think you need to run a flow check on your kitchen sink, labs, shower, etc. With my Rinnai tankless set at 120f with a 2.5gpm shower head I am running 2.1 gal of hot to .4 cold. The Rinnai boilers come with the 3"low loss header and the unit, in heat mode is doing nothing all day every day but maintaining a 36* temp rise across the unit, and short cycling "shouldn't" be a problem, but that said, what is your heat load?

If you are uncomfortable with the DHW output and want more your best bet would be the Q85s with an indirect. Rinnai has an optional 3-way valve that mounts to the unit and allow you to use the internal boilers variable speed pump to drive the indirect. You will like that system a whole bunch. If you do not want to use the optional valve you can run the indirect conventionally off the secondary side of the LLH, but you will need more pumps/controls for that.

I have to acknowledge my bias as I represented Rinnai for a long time and still consult with them.

On a pedestal

@ October 3, 2012 11:52 PM in pedestal sinks

You have to be dead nuts on your rough-in...or else. The left had threads is identified by the "cut" in the lands of the nut. Kinda hard to describe. On the flats where your open end wrench goes the surface has a slot cut in the circumference.


@ September 22, 2012 10:42 AM in Post Purge

You have discovered one of the primary reasons to have post purge. At shut down the pump stops the oil flow. The remaining oil in the burner is heated, expands and is forced out, peeing or dribbling into the chamber. No good! Put your post purge back on. Every system has a personality. You want a post purge sufficient to clear odors and reduce the heat enough to eliminate the "dribble".

NFPA 31 lacks

@ September 19, 2012 11:01 AM in Buderus chimney condensation problems

support for re-lining. We were never able to get the committee to include venting standards for re-lining. The excellent work on venting that Rick Krajewski and John Strasser did at Brookhaven in the early 90's got stuffed into Appendix E, never to see the light of day as it would raise system costs.

I will offer a conversation I had with Rich years ago about his work. What he said was that regardless of length, height, inside/outside, etc the thing that had the most consistent positive affect on flue operation was insulating the vent connector. Products are available for this. 4" pellet vent is L-vent and the DS and DVL products from Selkirk and Duravent, respectively, are excellent as well.

I spoke with a sweep from LI some time back who has been re-lining using App E for years and said the sizings are right on.

Mark's suggestion

@ September 18, 2012 10:43 AM in Using solar to heat my pool

Of a well fit pool cover is critical. As the NH nights cool you could loose all and more you may have gained with your solar system.

Pretty thin

@ September 17, 2012 10:40 AM in Luxaire warranties

On the reason for rejection of warranty claim. This is generally a process. How did this go down, both the compressor and the rejection of coverage?

I have had good luck

@ September 12, 2012 8:44 AM in Venting

with the Dura-Vent, Dura-liner product. I have it in my house currently. There was an old insert that consumed vast quantities of wood and produced no heat. I replaced that with a VC Encore and was easily able to adapt the existing Dura-liner install to the free standing stove. Excellent product in my experience. I represented Dura-vent back in the 80's when they introduced this product.

Good points, Bob

@ September 12, 2012 8:38 AM in Venting

As always, there's more than one way to skin the cat. The base support on the B-vent T can be an issue and in fact when I did my sisters place I opened the wall up a bit. Then I supported the tee with a section of Unistrut. I pop rivet the joints as they are lowered being careful not to penetrate the inner liner.

I have also done the flex liners and tried to insulate them. Honestly, I can't think of anything related to chimneys that is a bigger pain. The insulation hangs up and tears and I think you end up with more voids. This is especially so if the chimney is tight. I end up looking like Looney Tunes on the roof;) I'm very good at that!

I haven't done one of these in some time and perhaps someone has figured out a better way of insulating, but I'd rather have the B-vent. It was just cleaner for me. Where oil is and is likely to stay I don't see it as a viable alternative in todays world. Hate to say that, but...!

I would

@ September 7, 2012 10:02 AM in Rinnai RU98i only works with cover off

unplug the unit from 120 v. Remove th cover and see if all the exposed wires are securely fastened. Pay particular attention to the yellow wire to the flame rod. As well make sure the insulating boot is secure on the sparker. If that isn't in place it may be arcing to the cover. This is your installers job.

Silicone is a band-aid

@ September 7, 2012 9:58 AM in tankless gaskets

in this case. given that you were able to do this for so long without the silidope I'd keep doing what you had always done before. A good clean bearing surface is the key and then securing in the proper sequence.

The smooth wall

@ September 7, 2012 9:46 AM in Venting

is only one of the benefits of the B-vent liner. Probably the greatest benefit is the double wall construction which will protect the flue gas temp and eliminate or greatly reduce condensation. What happens in a flue is that there is a period on start-up where virtually every appliance will condense. Called the "wet-time" successful vent design with a properly sized flue will allow the vent to warm up and draw more quickly. Exterior chimneys are the worst and a single wall liner can be problematic due to the lower temps it sees. Also, and I do not have a current copy of the sizing guide, but do you really need 6" on a 30' chimney. Tim...Help;)

It might be a good idea

@ September 6, 2012 6:46 PM in Venting

to reline with B-vent. There are many single wall lined exterior chimneys that still condense like crazy. The double wall construction of the B-vent would better insulate the flue gas temps, and perhaps allow using one size smaller pipe, as you do not have the 20% derating of the corrugated pipe. Refer to your vent tables to confirm. If you go this way do not use Hart & Cooley Metalvent. They have a locking ring that increases the OD of the pipe and can become undone on the way down the flue. I'd suggest Selkirk or Dura-Vent

Do you have

@ September 5, 2012 9:45 AM in Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

24" from the other building? That is the clearance requirement for the heaters. For the water heater, I don't think the E model would be a problem, but it is worth consideration if you are right on top of the neighbors. As to commenting on the 110C list, please understand that the man who gave you this list is a licensed contractor in CA and he has to live with that system. I don't see anything superfluous in the list. He is on site and I am not.


@ September 5, 2012 9:34 AM in Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

by Rinnai are not approved for "closed loop" heating systems. They cannot pass ASME requirements and IMHO, never worked well in the field. As well, for the small number of sales they created an inordinate number of problems. Why compromise an otherwise excellent product reputation to get some systems out on the fringes.

Rinnai does allow the water heater in "open loop" systems. Those are typically a hydro-air system in an apt building. I'm not really a fan of open loop, preferring to keep my water streams separate, but I have to say they have worked well in that application. Those that I had experience with were all small loads.

The MC-91-2US controller you are referring to is the "Commercial Temp" unit. All the water heaters can reach 140*. To go over that you must purchase the Comm controller. On the 180kbtu systems you can get to 165*, the 199kbtu...185.

I go out on other sites and hear of people all the time who want to use TWH, for radiant jobs especially. Some manuf say it ok. My experience says it isn't a good idea and for years I got to see the catastrophes in a six state area. Tankless are designed to see variable flow and high delta T's. They are excellent at their primary task. For a pro to do these TWH closed loop systems you are really putting yourself in the crosshairs, imho. It's funny how customers forget how adamant they were for a particular system and if you agree to do it, well, you end up owning the consequences. ODR has no place on any TWH I am aware of. There is no place to interface that type control. If you need a boiler, there are plenty excellent choices out there;)

I always caution

@ September 4, 2012 11:51 AM in Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

folks from buying to many Energysavers. Keep in mind, these units want to do two things. Number one, meet your comfort demands and number two, do so at the lowest possible input and fan speed. With the constant modulating operation of the burner/fan they project the heat much better than the single stage on/off type units you are used to. From your wallets stand point these are the ultimate in zone control. I would buy two placing one 17 or 22 in the LR, either next to the door, between the LR/DR or, better yet under the window looking straight down the hallway. The other would go in the family room. Under windows is an ideal location for these as that is typically a harder area to decorate and you need only a 9" clearance from the vent termination to doors or windows. You can rough-in a gas line for where ever you think you might have a cold spot, but you can define those spots and treat them both with Airshares and additional Energysavers, but do not buy excess capacity. You will be surprised how evenly they will heat.

If you put a unit in a bedroom, do not use the 11. Use the 08. Where these make any noise is on start-up. You get pre-purge, spark, gas solenoids kick in and burner ignition. It isn't loud, but it is annoying if it short cycles. Min. btu on the 11 is 5500. At 82% that is in the area of 4400 net to the space which is a boatload for a bedroom and the t-stat has to turn the unit off. The 08 is down fired 08 to 3000 btu min or about 2400 btu to extend the run time in smaller spaces.


@ September 4, 2012 11:27 AM in Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

I wrote a lengthy response last night which must have been edited. Pretty sure I saw the "successful post". I'll try again later.

Back on topic

@ September 3, 2012 11:11 PM in Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

The Energysavers are tested and approved as Wall Furnaces and therefore comply with bank financing requirements. If they were simply "space heaters" you would have an issue. I think you will find that a unit at either end of the first floor will do nicely for you, but I have not seen the plans. makes a "problem solving fan" called the Airshare. Check it out. They are excellent!

You have discovered the limitation of combis. You select for DHW requirements and end up with to large a heating boiler in some cases. If you go with the heaters, go TWH. All of the Rinnai boilers have a 3" low-loss header. It provides a pretty good buffer against min flow rates. The boiler loop looks for a 36* temp rise and the house loop does its thing. The reset curve on the Rinnai boilers is very flexible. The Q80S will modulate down to 17k, but it is heat only and you can add the indirect or TWH.

I have a real problem with duct work. In fact when I moved into my hosue here in the foothills I tore out a 5 yr old central H&C system and went with the Energysavers. Should you choose to go with the York system you should demand in the contract that the system have "no leakage". CA permits up to 6% leakage on a new system. I'd demand better. Remember, you are talking day one leakage. What happens down the road. My feeling is that all of the unitary manuf (York , Lennox, Carrier, etc) can put all the technology they want in the box. They just can't deliver it! It is not the equipment. It is the distribution system.
I am a big fan of "net to the space" heating & cooling. Energysavers and mini-split heat pumps .

How soon are you moving ahead with this project?

Not sure where to go with this one

@ September 3, 2012 11:42 AM in Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

Heaters/water heaters? You have to be careful what you ask as I may end up writing War &Peace;) On the heaters, I just think it is one of the most undersold pieces of equipment in the business. I've sold over 180k of them in New England and am working them out here in CA on a part time basis. Apartment building conversions, straight residential as supplemental or whole house heating, basements and garages are the primary applications. I heat my house with them. fantastic product and another tool in the tool bag for a heating contractor. Most here are "system" guys and hence they do not get the play, but they are one of the best pieces of equipment I've ever seen.

Rinnai have gone to the Value, Luxury and Ultra categorization on the water heaters. Value are small residential and builder models to a price point. Luxury ( my favorite) are the .82ef units and ten the Ultras are the condensing models at .95, .96 EF. They are doing the residential of course, but more and more commercial as well.

Any specific question I'll take a run at!

Another option

@ August 30, 2012 11:00 AM in Hi-eff GFA + sep. Tankless DHW vs. NG mod/con RFH + DHW combi?

Given your open floor plan and small upstairs space, I would suggest you look at the Rinnai Energysavers. An EX11 upstairs and perhaps two EX22's on opposite walls downstairs would give you more than enough capacity. You could do the downstairs with the one EX38, but I prefer the zoning capability of the two smaller units. All are net to the space with no distribution system, quiet, cool to the touch, modulating burner and blower, built in programmable t-stat and are a simple install. I live in Nevada City and heat 1400 sq ft with two 22's. Both are downstairs and I like the bedrooms somewhat cooler than the primary living space downstairs, but they are only about 3* cooler. With that, your choice of the 98 tankless will provide 5.3gpm at a 70* rise at a .95 EF...all day long. The RL94 will do 4.7 gpm at 70* rise

The Rinnai tankless for space an open loop system works, but in my opinion would be the last of options you list. I do not like tankless for space heating. They work, but it isn't what they were designed for. You want to do this once. Therefore, use equipment for their primary design spec. The tankless space heat option is cheaper, but that is all it is! In the good, better, best world tankless space heating is somewhere below there;)

The Rinnai Q80S will modulate from 17-80kbtu. The unit requires primary/secondary piping, but is supplied with the low-loss header and the internal variable speed pump. Should you choose the boiler and an indirect there is a three way valve option that can be mounted on the boiler which allows you to use the boilers internal pump to drive the indirect.

Now, in fairness, I must say that I represented Rinnai in New England for a long time and am working with them now in a consulting capacity, so bias noted.

Cost is always in play

@ August 6, 2012 4:33 PM in Best product for domestic hot water?

First you need to provide a bit more info. 4 baths and a kitchen. What is the lay-out of the four bathrooms? In the master, are there any high flow fixtures? What is that flow rate on that fixture?

Once you have that info you can lay-out a solution using tankless water heaters. Depending upon the floor plan you may be able to group them together. If the load is really spread out you may want to break up the system. Get asp close to the major loads as possible. I'm a fan of Rinnai;)

I'd be more concerned

@ July 23, 2012 10:23 AM in Uponor Joist Trak & Uneven Subfloor Panels

With the hi/low on the plywood. What type flooring goes above it? If it is tile that seam could give a real problem in the futrure. At least it could be a squeaker. Get the floor set correctly and your problem goes away.
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