Large DHW but very small heat load

hot_rod

I spent last week in No. Cal and shared some training classes with Paul Rohrs of Lochinvar. My presentation was on buffer tanks, Paul covered boiler piping and the Con X Us system. Buffer tanks is the topic for the next Idronics, also.

So it's not unusual in the bay area to have a DHW load requiring 200K and a heating load of 50K. Even though water is scarce there are a lot of large DHW load jobs. Wineries are a classic example.

I learned a lot about the new Lochinvar features like the Con X Us which allows you to view and adjust the boiler from your phone or tablet, free ap. They also have wireless sensors available to add or correct poor sensor placement.

I thought about using the "ramp delay" feature to allow the boiler to go to high fire, high temp for DHW, then limit the output to say 25- 30% with the ramp delay, using up to 6 steps to ramp slowly, for small heat loads.

We are also showing a 2 connection method option to pipe buffer tanks. The large piping at the tank becomes the separator, but mainly the boiler can go directly to the load without "seeing" the tank. So, if the DHW was generated via the plate HX, which could be sized generously to allow a close approach, the tank could be maintained at a low temperature. Assuming the heat load could be met with low tank temps.

I've found with a 30 plate HX I can generate 3 gpm, warm enough to shower, maybe 103F with the tank as low as 120F.

I like the idea of a separate buffer as it can be well insulated and does not have any exposed metal or flue. My solar Phoenix works great, but it does have standby loss.

The new Euro standards have insulated tanks wit 3-6" of insulation now. Maybe that will be an upgrade to the code here some day, better insulated storage vessels.

This drawing, from Idronics 17 shows 2 pipe buffer, the biomass boiler could be excluded of course. The buffer is still a pl,us for micro zoning and near endless DHW production.

hot_rod

Here are the screenshots of the Lochinvar Con X Us ap that allows you to make changes. Slide the buttons to make changes in real time. Pretty clever.

So you can "electronically" limit the boiler output and regulate how it steps up. Also make adjustments to ODR.

Henry

We have encountered a number of small apartement blocks (15 to 25 units) that have been converted to electrical heating for each apartment. Only the public spaces have hydronic heat. HTP Versa Hydro was the perfect match to a low 50K heating load and high DHW demand.
http://www.htproducts.com/literature/versahydrobrochure.pdf

hot_rod

Yep that is a nice package.

I'm just offering options when space isn't the determining factor.

I was intrigued with the ability to set, view and adjust the Lochinvar from an online connection. And the ramp delay to allow the boiler output to be sized and downsized to a small load.

When you put all your "eggs in one basket" with those combo tank, you have an expensive replacement should the tank leak.

Pros and cons both ways. With separate components you can mix and match brands and sized to your liking.

Henry

S/S steel beats the competition and the location of the modulating burner gives it also a major advantage even over those that now modulate.

hot_rod

There are areas in the US and Canada where stainless tanks or SS tankless don't hold up well. So a glass or stone-lined tank and separate boiler are the common approach.

Also still plenty of cast iron boilers being sold and installed ECR claims about 50- 50 cast to mod con sales.

I like the wide turndown available with boilers also, larger Lochinvars have 20-1, dual burners into one combustion chamber, for example. That opens some nice opportunities.