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Joined on March 1, 2007

Last Post on April 4, 2014

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The thing about tankless and Solar

@ February 17, 2013 12:57 PM in Tankless WH as booster

Actually let me rephrase that. The thing about Rinnai and solar...I can't speak to other manuf as I don't know all of their specs, but it all pretty much starts with GPM X Delta T X 500= BTU. In order for the Rinnai's to initiate operation the unit must see a min of .4 gpm. Once it starts it will hold operation down to .26 gpm. On the RL94/75i the min btu is 10,300.
In the worst case you have to have a pretty hi delta T (around 50*) at the. .4gpm rate to initiate fire. You can push those numbers around and get operation at higher initial flow rates with a lower delta T.

A good solar system design in my opinion is to by-pass the tankless until you get a low enough solar tank temp to allow the delta T and flow rates to begin to let the tankless do its thing. I also don't like to simply run the water thru the tankless as all you are doing is driving the limits due to the high temps the solar tank can provide.

If I am not mistaken, and perhaps Mark will chime in here, Caleffi makes a 3 way for this type application. By-pass the tankless when there is sufficient hot in the tank. When the tank drops to a low enough temp, and you have to spend some time on setting this up, the 3 way diverts back to the tankless and it peaks the hot water.

I'm just re-modeling the house and want to install a system to do this. My problem is I have to do a sun-map to see if it is worth doing. My house sits under a very large Black Walnut, a 100' tall Ponderosa Pine and about 125' Sequoia, so it may not be worth doing;)

I have had cross connections

@ February 3, 2013 9:58 AM in Cold showers?

in houses that have driven me nuts. Getting out of the mechanical room for a bit and something you can do and save yourself some dough is to do isolation runs with the hot water. Washing machines can cross flow. Shut off the valve and run your hot water tests. Every fixture has a hot and a cold. turn off the colds and see how the hot runs. Bring on the colds sequentially and see if it makes a difference. Do you have tempering valves on your toilets? In order to eliminate condensation on the toilets people have installed tempering valves that put warm water into the toilet. They can definitely back-flow and have produced exactly the type situation you are talking about.

My Henry, but you are persistent

@ February 2, 2013 7:49 PM in Rinnai Water Heater - Water Not Hot Enough

with this comment. I'd be interested in your story on this topic. It is hard for me to believe that all those few hundred thousand people per year who are buying them are unhappy;)

To the original poster. Put a hose on the hot water outlet service valve and close the valve to the system. Set the unit to 120 and read the outlet temp on that water. That will by-pass your system entirely and give you a good hot water test. Get you install manual and get the sequence to read output temp and GPM of hot water flow. Report back!

If it is all radiant

@ January 26, 2013 10:48 AM in Rinnai Boiler Excessive Fuel Consumption Problem

You should be on reset curve 4. Again that is in the parameters menu. Switching boilers is the last thing you want to do. Let me repeat, the last thing you want to do. The programming is simple...Once you have done it a few times. You have the manual. Follow it carefully. Before getting into the programming mode, examine the options and write down what you need for that specific parameter. Then go at it. As you step thru the parameters write down the default settings on your boiler.

In looking at it, I think you need to adjust parameter #2 to 4 and calculate the vent length altitude compensation factor for #73. The worksheet for 73 is clearly laid out in the manual

What is the heat loss for your home? Any information you provide should be prefaced with that info.

Get your dealer onto the Rinnai tech line

@ January 25, 2013 4:23 PM in Rinnai Boiler Excessive Fuel Consumption Problem

800 621-9419 Trying to analyze fuel usage while under construction is kinda hard. Your fuel consumption figures of 2.3 gpd or 5gpd does not seem excessive. At 5 gpd you are looking at about 19000btu/hr of heat loss. That is not excessive.

There are 4 programming chapters in the unit. Parameters for set-up, Info for 18 specific details from water temp in /out, outdoor temp, % of power, total seasonal consumption and a bunch more. If you look into the INFO section of the display the boiler will tell you exactly what it is consuming and also give total energy consumption in kWh (1 kw = 3,414 btu). You also have a Service and Error section. Have your dealer show you the Info section, but DO NOT fool with Parameters. That is his job.

Has your dealer done a proper set-up on the unit? Did he use an oxygen analyzer? What type distribution system do you have? Baseboard? Radiant? Combination? What re-set curve is the unit operating on?

I'm sorry to play 50 questions to your questions but you are getting the idea. I could throw a dart at the question but need more info. That is an excellent unit and will heat your house well and efficiently.

I'm with Ice on this, for sure

@ January 21, 2013 10:23 AM in Large heating bills - where to go from here

Making equipment decisions based upon an envelope you intend to tighten, but have not yet, is really not the way to go. You have heard that old saw about not putting the cart before the horse? Well, this is it! Get the envelope tightened. Create that stable thermal envelope, see how it does, and then make your decisions on heating gear. My old house in MA was not well insulated and had lousy windows. The first year I re-sided, wrapped, re-insulated and put in new, not replacement, windows and there was a profound difference in that house, not only energy wise, but it was quieter in the house as well, with reduced road noise, etc.

Apparently I didn't learn my lesson as the place I moved into here in CA had NO insulation, until I had the place "drilled and filled". Meeting the architect this morning to go over the re-model. Call your utility or local energy auditors to get an analysis of the building and see what you have.

The cabinet

@ January 20, 2013 2:49 PM in Rinnai RU98i only works with cover off

on the RU model provides the combustion air chamber, meaning the CA enters thru the outer pipe in the concentric vent and then is pulled into the intake"horn" on the lower mid- rt side. Therefore, with 12 error code I would say that you need to check the vent to make sure the joints are secure and make sure you are getting no recirc of exhaust gases from the termination.

On your 110 I would suggest that you pull the kill the power, remove the cover and check to make sure that all the electrical connections are secure. You should be able to see if you are pinching one or it is kinda sorta connected.

Paul posted this on multiple topics

@ January 18, 2013 2:17 PM in Rinnai R53i-1

The Main Wall, gas heating and here on DHW. All comments are not in one section, so

Something to look at.

@ January 18, 2013 2:13 PM in Rinnai tankless woes

Check your vent termination and the joints on the vent. Is it clear around the vent termination? It is possible that a condensing unit, garbage can, etc may be impacting the vent and re circing exhaust gases. Perhaps one of the joints is partially dis-lodged and in a low fire condition not cross contaminating, but under high fire flue gases are drawn into the fresh air side.

Your error code 14 on the first unit is in the safety/limits circuit. An open limit will prevent operation. That is a simple series loop and with a digital multimeter the open limit could be identified.


@ January 14, 2013 11:12 AM in Misc questions on radiant

I would not even consider the geothermal. You can put in mini-split heat pumps and operate at a cost very close to the geothermal for far less dough. This is absolutely worth a look. The best brands are Fujitsu, Mitsubishi. Where are you located?

Thanks Alan!

@ January 13, 2013 11:37 AM in Reading list

I've only been noodling around this site for I don't know how many years...;)

Your reply doesn't

@ January 13, 2013 11:35 AM in Rinnai R53i-1

mention the heat exchanger. Adding the drain and replacing the gas valve are the supplemental issues at this point. The real issue is the hx. If, and I am quite sure this is the case based upon what you describe, the fins are "healed up" with the evaporated condensate you are going to create hot spots that will create a leak in fairly short order.

I think the instructions are supplied with the valve, but if not make sure you call tech service to walk you thru the process.

Here is another thought. Pull the inducer motor and look up into the bottom of the burner tray. If water has gotten into that area, which is likely the air distribution holes in that area will be healed up. When you pull the burner tray clean those up as well.

Who installed this? Was it a homeowner job?

Reading list

@ January 12, 2013 11:47 AM in Reading list

I have had a few people recently ask me what books they should have for hydronic training and reference . Fact is, when I think of it I could use them too because every time I begin to think I'm a pretty smart guy, something, well, comes up;) . So...If you were to suggest a reading and reference library of say 5 books, what would they be?

If there is water in that tube

@ January 12, 2013 11:42 AM in Rinnai R53i-1

You are looking at a new gas valve, absolutely. That tube is connected to the bottom area of the burner chamber. It has a nipple that sticks up probably 1/4-3/8" from the bottom so water cannot easily get into this tube. There has to be a LOT of water for this to happen.

My suggestion, having done a lot of these, is that you lift the vent and inspect the head of the heat exchanger. Rinnai specs 5'vertical, max , without a condensate drain. You are at 14'. The condensate is flooding the vent trap and dripping onto the hx. On a call for hw it fires, boils off the water and leaves behind the crap you are going to see on the fins. That is a 3 row coil so if it is really crapped up, and you will know, it is also time for a hx. Additionally, your intermittent fire is due to the condensate dripping thru the hx and hitting the flame rod. That will interrupt the flame current and error 12, if you had the controller. Once the moisture clears the hx it then goes into the burners and further spreads its joy, which if you have water in the gas valve tube it has certainly done. If you end up repairing this unit, you will have to clean the affected burners. There are 16 identical burners in that tray. Once you clean the 3 or 4 affected burners take those low fire burners, which will be the affected burners and move them to the far left of the burner tray. Put the original three on the left in the low fire position. Having seen a lot of these improper installs over the years I can tell you that you will save time by disconnecting the unit from the wall and laying it on its back. This is a 5 min job...if they installed the isolation service valves and if the vent is properly supported.

This is straight out a fault of the improper install. That is a good unit, when properly installed. $2 worth of clear vinyl tubing would have prevented this, as well as an installer who bothered to read the install manual. Mad Dog, as usual, has a point. You have to inspect this and looking at parts and labor determine the best course of events. Let me know if I can help further.

In this circumstance

@ January 7, 2013 2:08 AM in Boilers for small apartments

I think you and the tenants would be quite pleased with the Rinnai Energysaver that KCop references. We have done more than a few tens of thousands of them in apt buildings all over the Northeast. They are a simple install and last a very long time. A good value in other words.

I represented Rinnai for 20 yrs in New England and still consult with them, so please note my bias, but, then again, I heat my home with them:)

Check them out at

Radiant may not be your best option

@ January 2, 2013 10:47 PM in Sun porch in winter

Simplest effective solution imho is a Rinnai ES 38. Check it out. Do try to tighten the envelope

Radiant may not be your best option

@ January 2, 2013 10:47 PM in Sun porch in winter

Simplest effective solution imho is a Rinnai ES 38. Check it out. Do try to tighten the envelope

Not to contribute to the problem...

@ January 2, 2013 10:42 PM in Fujitsu defrosting hourly

What temperature is it outside? My 12RLS goes into defrost a few times a day and may take 5-7 min to defrost. That comes in at around 32F. It then immediately comes back on and rocks heat output wise. Your refrigerant pressure may be low.

Dear Sir, Our Original Poster

@ January 2, 2013 10:35 PM in Point of no pressure change - help me understand

I am not even going to attempt to get into this. This is the Third Rail of Hydronics...regardless of what Dan says;) Having just come on this evening and seen the time of original post and number of responses from guys I look to for advise, you get the award for the, The Question of the Year. Had you asked on 12/31 you would have gotten the Question of 2012 too! Well done!

This is always the lead

@ December 31, 2012 11:20 AM in combi heat dhw gas

on combi's. You get a customer interested or they are interested initially and the conversation has to start with DHW production. You have to ask the homeowner how much hot water they need and you need to get ownership from them before proceeding with a combi. That my mean doing flow checks on fixtures. The other issue with a combi is water quality. A crapped up plate will not do you much good down the line. I like to see them installed with the same type service valves installed on tankless water heaters so they can be flushed.

Ran into a fellow

@ December 24, 2012 7:21 PM in Amish Heater - Electric Fireplace

Who had just put in about a 3kw PV system at his home. Net metered. As he had that he figured he would use these really efficient Amish htrs...4 of them to heat his 1200 sq ft home. There was some disagreement as to how much the utility had to pay him for his PV power. The disagreement lasted a few months and when they finally figured it out they sent him a bill for $6,800 net. Freaked him out! Tell him to save his money, just get two metal drop lights with 100 bulbs. Put a computer fan behind it and string a piece of the red paper in front of the bulbs. Voila, efficient heat!

I kinda look at these things as the great lie!

Reminds me do my 2nd yr apprenticeship

@ December 16, 2012 1:17 PM in Furnace repairs DIY

In Upstate NY in 72 there was an enormous flood and we were trying to get people into HUD trailers. At that point I had no problems running black gas pipe, but this coincided with about the first electronic ignition systems from Honeywell, which were in all the furnaces, and I had not a clue...but had to get the heat on in these trailers. I had one that hung up and would not ignite. I'd try it and then wait as prescribed and try again. This went on for a while and finally I got a spark. Well, at that time I had this enormous beard/mustache. When the fireball came out of the face of that furnace I was backing up at light speed. The furnace was in the hall way and my back hit the side of the trailer. I actually put a belly in the outside of the trailer. I had a sunburn and my beard, mustache, eyebrow and lashes were Rice Crispies.

What I learned that day was to not screw around with this stuff...and always look at what is behind you when working? One again boys, life is a humbling experience!
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