Scary water heater replaced by Lochinvar 98% thermal efficiency unit.

JohnNY

We just completed a real nice job in Brooklyn's Park Slope area.

A 17-unit building needed to replace a 35 year old 825,000 BTU water heater. It was an '80s version of an on-demand unit with no storage.



We replaced it with a 200,000 BTU, 98% thermal efficiency unit with a 120-gallon insulated storage tank.

I'm very impressed with these Lochinvar units, our clients are happy as can be and they paid with pleasure.



Winning all around!



Pics on Flickr:

<a href="http://www.flickr.com/photos/gatewayplumbing/5600329009/">http://www.flickr.com/photos/gatewayplumbing/5600329009/</a>



<a href="http://www.flickr.com/photos/gatewayplumbing/5600907710/in/photostream/">http://www.flickr.com/photos/gatewayplumbing/5600907710/in/photostream/</a>



<a href="http://www.flickr.com/photos/gatewayplumbing/5600321419/in/photostream/">http://www.flickr.com/photos/gatewayplumbing/5600321419/in/photostream/</a>



<a href="http://www.flickr.com/photos/gatewayplumbing/5600900872/in/photostream/">http://www.flickr.com/photos/gatewayplumbing/5600900872/in/photostream/</a>

Henry

Knight

One of our transformations from las August was taking out two 2 year old RBI and replacing with a single 500,000 BTU Knight and a braised plate heat exchanger. The client sent me his gas bill as he was extatic: 38% savings!



Here are the before and after pics.

JohnNY

My pics

What do you think?

NYplumber

Sizing

As always, meticulous install John.



How does one go about sizing the required btu load and storage tank capacity on a retrofit?



For space heating we use a number of the available computer software programs to come up with a decision. I am interested to hear more about dhw.



Thanks in advance John.

JohnNY

Sizing

Thanks, NYplumber.

Truth be told, I don't like the typical sizing methods for domestic hot water heating. They're often a cover-your-butt, worst case scenario calculation that results in overspending for equipment and energy.

So, along with my Lochinvar rep, we did some sensible calculations with about 75% of the potential demand running and came up with a much more realistic BTU and storage capacity.

Brad White

Good engineering, John

Congratulations on having the foresight (and guts, sometimes, frankly), to assess the true demand and sizing accordingly.



I was impressed with the Lochinvar factory, engineering and manufacturing, including the QA/QC procedures. Very much state of the art, as good as any in Europe I have seen. Lochinvar engineers tend to "think like the user" and their controls and applications reflect that.



Now you will show them the value of storage in such a system. We know that on-demand systems bring along constant cycle losses for each hand-washing and that hot water through-put is the dominant energy variable. But now their production costs I would expect to be noticeably lower. I hesitate to put a number on it, but we all have a number in the back of our heads.



All that and another neat installation worthy of your last ones, as always.

JohnNY

Thanks, Brad.

I know I can always add to my btu storage by raising my temperature and adding a mixing valve, so I'm willing to take the shot on lowering the anticipated demand on my calculations.

So, maybe I don't have so much "guts" after all.

Hope you're well.

JC

tim smith

Re: Lochinvar and dhw supply

John, nice looking job. We approach our hot water supply the same way. We have always used AO Smith sizing charts for multifamily and keep pretty close to their #s which will come up with not way over sized system. It is amazing how much diversity of use there is in a 30+ unit 1br apt bldg.  It is not uncommon for us to feed this size of building with a 119 gals Superstore tank and 175mbh triangle tube solo  and we always supply enough.  This could be in future either still Triangle or Lochinvar.  Our ideal systems on these old 1920s brickers are 2 of the TT 175 boilers, the indirect fed off one of the boilers due to asme requirements and both boilers available for heating the building. Slick set up.  

Henry

Lochinvar Armour

Here we disconnected an atmospheric 1.4 million and replaced it with two Armour 500 in a 70 unit 1930 apartment building. The savings during the whole year was nearly 35%. The same customer had a 160 unit plus a dry cleanner and there, we used one 500 because of the 4000 gallon storage capacity. It is prefarable to use more horse power (BTU) than less with more storage. The boiler or boilers will condense and less BTUs are lost by the storage system.

Henry

croydoncorgi

Light in tunnel = train coming? !!

On-demand versus stored-water system.  Interesting choice....



I've never done any units as big as that but I wonder about the overall efficiency and cost calculations for the two approaches.  Yes - if you have a big buffer tank you can make use of a smaller burner / heat source with presumably smaller heat loss overheads.  But there are costs of the storage tanks, extra pipework etc. to consider....



I have had situations where it made total good sense (on efficiency AND cost grounds) to replace an obsolescent stored-hot-water system with an 'instant' heating replacement (eg. Rinnai).  So long as the instant system is capable of driving a 'hot loop'  (recirculation system) and the mains supply for water AND gas is capable of meeting the maximum load, then it still seems to me that for small systems a 'combi' boiler is best, for medium-scale an instant-heat system for hot water alongside a high-efficiency unit for space heating, then (at some scale) probably stored-water for very large systems.



One of the drivers for this in Europe is that it's hard to make a modern condensing boiler run efficiently when it's at the high temperature (75C, 170F) needed to reheat a water tank, so dual-mode combined heating and hot-water systems are harder to do.  One argument AGAINST instant heating for larger systems is gas demand: even a 26 litre/ minute Rinnai needs 50+ kW of gas input.  That puts it uncomfortably close to the maximum capacity of the 'standard' UK gas meter - 6 cubic metres per hour.  Doesn't leave much over for anything else!



I like to hear other opinions on this.