How would you do this?

heatpro02920

OK, so I have a project that we are giong to start for my brother in law as soon as the heating season ends before we move into ac {a couple Sunday afternoons job}..

labor is going to obviously be free, he is paying for materials.



The house is around 2100 sq ft with a heated garage {slab} that is around 500sq, the total heat loss comes out under 100K BTU's... There has been 2 major additions to the property one being the garage and the other adding a master suite, both the master suite and garage have radiant while the rest of the house has baseboard, which is under sized the boiler temp is set rite under 200 degrees and some parts are still hard to heat.

He has an old gas boiler and a 3 year old indirect that is no longer in use since I installed a Rinnai last year.



So what I was thinking was this...



2- TT solo 60's {not cascaded} one for the hot water base board and one for the low temp radiant. His current radiant system uses mixers and its an older system, some serious joint flowers and other signs of corrosion present, plus a couple of the mixers need service... So I will get rid of the mixers all together, install a bumble bee on each zone.



Pretty simple EXCEPT, I was thinking to use his 3 year old ss indirect instead of tossing it away, I will install it in the system, I will pipe its boiler supply and return into the return of the high temp boiler, then its DHW connections into the low temp boiler.



If my theory is correct this will create lower return temps for the high temp boiler and help take care of the low temp side...



I'm just in the thinking stage rite now, any ideas would be appreciated, I still have to do the exact math for his house {flow rates, btu, heat loss, ect}.. heres a pic of what I am picturing for a design layout, I will use the aqaustat on the indirect to control a zone valve assembly on the low temp boilers return so it will only allow the return to go through when the indirect is hot, makes no sens to let the low temp side heat the indirect if the other boiler hasn't ran... I will either use a normal 2 stage zv between the tees or maybe a 3 way instead of a tee, depends how I feel at the time I guess...



ANYWAY what are the pros thinking?

Timco

Sorry...

Stopped reading after "Brother In law" and "free labor".

heatpro02920

Yah worse kind of job, lol

The free ones aren't much fun and it seems they are the ones that complain when its done...



But it is what it is..



C'mon guys no ideas? I couldnt have gotten it perfect frist time out of the gate, what would you change?

Zman

Less is more

I am looking at a similar job right now.

It has a little less heat loss but also has a hot tub heat exchanger that needs about 20k/btu.



I am thinking of using a Lochinvar WHN110 and the Lochinvar 3 temp mixing add on controller.



One mix temp will be high temp Hot water baseboard.

One mix temp will be low temp infloor heat

The third temp will be the hot tub which I think will run at about 140.

The DHW will be a priority indirect tank



One boiler, done deal.



Carl

heatpro02920

the tt can do dual temps...

But I prefer dual 60's vs a single boiler. I don't install lochinvar I install TT mod cans... I like to stick with a single brand.... If a customer requests something or the rebate program is pushing alpines I will install it but when I have the choice, I choose what I am selling at the time...



I haven't looked into lochinvar in a while, I am going to check out that control... thanks

Harvey Ramer

Do yourself a favor.

Free labor. Brother-in-law and such.... Install a regular system that you won't be married to. You'll thank me later.



Harvey

heatpro02920

one of the benefits to

doing the job for free is that I can get a free beta tester... I have done something similar with a plate exchanger and a single unit, run the DHW through a plate exchanger on the return side to preheat the dhw and drop the return temps...



I dont foresee any design issues, 2 solo 60's will be reliable and there isnt much more to it than a 3way zone valve and the indirect which he already owns...

Zman

Triangle Tube

I love the TT boilers.

They don't really do 2 temps at once. They will always default to the higher temp. This does not work with extremely different temps With TT you need a 3rd party controller to do mixing.

I have yet to get my head around why you like installing a demand water heater and a condensing boiler.

The idea of 2 condensing boilers is good if you cascade them in order to increase the turndown ratio and provide redundancy. Running them on separate loads does not do this.

What you are proposing will obviously work. I just see complexities with little benefit.

Carl

Big Ed_4

Yes ...

... every Thanksgiving if you get it wrong

heatpro02920

dual temps

I have configured controls so they can do dual temps, but its a pain and not cheap...



I do a lot of Tankless and separate boiler installs, in my brother in laws home his tankless is 30 ft from his boiler room, mounted over his washing machine, which is directly under the kitchen and 10 feet from the master bath...



In my own home I use a separate Rinnai unit with a mod con boiler for heating, there are many benefits, Its a tankless so you don't run out f hot water, very even temps, when I am not home the tankless isn't heating water, 90+ efficiency, ect {you guys know the benefits to a tankless so I am not going to list them all}...



With a tank, you need higher boiler temps, you need to run your heating system year round, tanks don't last long, you can run out of hot water, temps arent as even, no way near as much control, more piping and wiring with a tank, you sometimes need to oversize heating boiler to supply tank enough energy to satisfy dhw, ect ect ect I can go on and on why it makes more sense to go tankless



Now there are some negatives... Tankless needs a separate vent, not a huge issue in most cases but can be a pain to the installer, tankless needs a separate gas line, parts and repairs can be tougher depending on location, but if you have the rite contractor {like me} I stock them and keep a few loaners on hand, if there is an issue, I will take yours off the wall and put a loaner up {takes 10 minutes}, then bring it back to the shop fix it and return it... This is rare since they don't fail often and when they do its normally something easy... I had 2 service issues with all the rinnais I have out there this year, one was a wet interior flood sensor due to condensation {they had an ac unit blowing in the room and it caused a wet cabinet, and the other was a bad flow caused by a clogged filter...



Now as far as cascading the 2 60's that would defeat what I am trying to accomplish, because I dont want to have to mix the radiant zones, I want a low temp boiler and a high temp, the 16K btu low end mod will be close to perfect on both sides...

Zman

Mixing

I understand your thoughts on tankless.

I have always done indirect and they work great. I am pretty sure they cost less and last longer than tankless units.

The lochinar ,or triangle tube with tekmar, will let you do one temp high and then mix the other temp. When only the low temp is calling, the boiler(s) turn down to the lower temp and the mixing valve goes wide open.

I am on the less is more/keep it simple program. When ever possible I will use one appliance rather than 3.

Carl

heatpro02920

Carl yes I agree with everything you said...

BUT, in this case...



He has the indirect, just sitting there not being used, I do not want to mix his radiant since all of his mixing valves are either leaking or in need of repair {all but one}, I did the math today when I was at the office and the price of 2 solo 60s vs a single 110 is only $800 more after I figure in the entire parts list of doing it each way....



As far as reliability, I can not count the indirects I have changed under warranty {granted there are many more out there}, but I have installed many rinnai tanklesses and I would have to say the failure rate vs a tank is much less.... When installed correctly they are very reliable... I have at least 20 of them out there being use as heating units which they are not designed and they are still working after 10 years with out issue...



I replaced an amtrol indirect today under warranty, I have 2 ao smiths directs for warranty rite now, and I am waiting for weil mclain to get back to me with an rma for a 40 gallon so the customer can get credit for purchasing the tank Friday of last week...



Around here indirects are not reliable.. I can list almost 10 not including the ones above that I have changed since January... As far as direct tanks go I wouldnt know where to start, I have changed so many lowes and home depot tanks I don't even get the tanks when I return them, I just get home depot or lowes store credits and install a bradford white from my stock... I wait until I have 5 or 6 before I take them in, all at once...



Tanks are tough business, it seems like the ones from 20 years ago lasted, and from 10 years before that lasted even longer but now to get one to last 10 years is a gift, and when you do the math- 1- $1400 tank every 10 years or a $2000 tankless every 20 plus save a little energy at the same time, its not too hard to make a decision...



I have yet to have the customer ask me to remove a rinnai unit, and my warranty is "If you don't like it, I will take it back, install a tank and refund the difference!!!"



Carl go over the numbers, you may be surprised, I can install a straight forward Rinnai unit in around 3 hours, some times less and the max is 5 hours if the venting and gas lines are tricky... An indirect {new install not direct replacement} is also about 3 hours...



As far as cost of materials that is tough did you ever price an indirect that can provide the same endless water as a tankless? and the tankless is stand alone vs the indirect is taking life away from your boiler every time it calls for heat...



Once you start selling them and seeing the happy customers, they aren't the devil like some of our local guys like to think, which is fine with me, since I get all the installs

Zman

I see

This is a good conversation.

Some of the difference may be the water. In Colorado the indirects hold up pretty well. I have seen some really plugged up tankless units.

The tankless units get derated pretty far for altitude and the water coming out of the ground is really cold. That makes for an uphill battle.

We also have a very long heating season so the boiler is already hot.

Love your posts,

Carl

NYplumber

Low-High temp hybrid?

At least this job you know its free upfront.



How about a high and low temp hybrid system? Have the two boilers feed a buffer tank. Use a condensing boiler of your choice with a high temp wet base boiler as the high temp source. Control it properly and you will have efficiency, redundancy and have your experimentation.

heatpro02920

This was my original intention

I wanted to use his current boiler {it would be oversized for just the high temp side but it would work} and then add a solo 60 for the low temp side, but when I mentioned it he let me know that his intentions are to use the chimney for a new fireplace and needs the boilers hung on the walls opposite where the current system is....



This would save initial costs and work great, but not going to fit...



thanks