outdoor reset...again

Larry (from OSHA)

by all of you that responded to my last thread about reset for residential use that there are few things in life better than outdoor reset. That said, now that I'm going to add it to my boiler, I would appreciate some more input. I've got a Weil McLain HE series 2 boiler. It has an induced draft. I'm concerned about condensation from too low of a return temp. It has 3 zones on demand with 1 taco 007 circulator. Delta T of about 20 degrees. Currently, there is no bypass to mix supply with return. This system has run just fine for the last 20 years, by the way. The design temp is about 190 as I'm in Minnesota. So, questions of the day: do I need to add a bypass loop for protection for condensation or boiler shock. If I run the low temp down to about 140 on the supply side am I looking for trouble? And most importantly, what am I missing???

As before, I am greatful for any input you can provide.

P.S. My day job is involved with safety issues (OSHA stuff) If I can answer ANYTHING safety related, please just ask.

Thanks

Larry

Justin Gavin

I hate the Vikings....but here you go

I would suggest adding a boiler bypass to allow the return water to come back at a minimum of 140. I live in Wisconsin myself and have these few thoughts for you.

I know I might get bashed for this but here it is

Before you spend money on the outdoor reset I would spend it on better insulation & better windows. I can assume your home is older (you stated that your boiler installation is 20 years old.)
If this is the case than better insulation will serve you better on those mild days where the outside temp is 45 to 55 but it may be 60 in your home. That insulation might keep the temp at 65-70 or so which is pretty comfortable for most people. I live in Green Bay and we normally start putting our heat on around Mid October until about Late April Early May.

Now with that said if your insulation is up to date and you have good windows and you still are looking to save a few bucks here is another thought.

You sound pretty handy why don't you try to manually set your operating temp to 160 or 170 for the next month and see if you can stay warm with that. See how long this lasts for you and if it isn't keeping you warm bust it up a notch or two. Keep track of what temps you need to keep your boiler up to maintain comfort in your home and work off of that. Just be sure to try to maintain the 20 degree delta T and make sure you don't go below 140 degrees on your return. It is a hell of alot cheaper that installing an outdoor reset. If you plan on doing this I would still install a boiler bypass valve to protect your boiler just for peace of mind. They cost about $150.00 and are pretty easy to install if your system is drained and dry.

Now if you don't want to fiddle around adjusting your operating control than get the outdoor reset and install a bypass.

Good Luck...By the way who would of thought the Vikings would still be undefeated???

Good Luck,

Justin

LEAD PIPE

'

LEAD PIPE

I did

Go Vikes!!!!!

Larry (from OSHA)

The Vikings will

most likely choke in January or so, as they always do. As for the house, the insulation has been bumped up to about R44 in the attic and the windows are not bad nor great, but are not a candidate for replacement. As for manually setting the high limit, I am adding an indirect dhw unit and want the control to do both priority and bump up the temp to the high limit with a call from the hot water heater. The Honeywell AQ475A is what I'm considering do to price and features. The Tekmar is way to spendy for my tastes, but it does have lots of features. As for the Vikes, I don't think I know anyone who would have thought they would be where they are. Hope the Pack comes back.

Take care and thanks,

Larry

Radiant Wizard

Reset The System

not the boiler. This will give you the boiler protection you need along with a much more flexible system. I would recommend primary/secondary piping utilizing either a modulating 3-way mixing valve or an injection pump.

heatboy

Every system I can think of........

would be more comfortable utilizing some sort of reset technology. I have never done a complete radiant project without having reset involved. It doesn't make sense not to. Yes, it will save energy, but that's not the reason I include it. When it comes to true comfort, reset is it. I have reset everything from radiant floors to cast iron radiators, fintube and even hydro-air. It doesn't matter at all what your system design temperature is. With reset. it's always on regardless if your system design spread is 30° or 130°. Temperature design and spread has more to do with surface area than anything else.

Have you ever been in a house that has cast-iron radiators and is hooked to a boiler that utilizes a tankless coil for domestic hot water? The comfort level is horrible, akin to forced air. Adding reset to the system via a mixing valve or injection pump will increase the comfort 10 fold.

The biggest issue you will find, is finding a contractor who is familiar with reset.

hb

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Mark Hunt

Good advice Justin


Improving the thermal envelope on a home is always a great place to start, although replacement windows are usually very expensive.

The catch here is that as the BTU loss for a home is reduced, the heating systems become more oversized for the load. That would include the radiators or convectors.

So now we have a home that will satisfy the heating demand with lower water temperatures and no protection for the boiler. Short cycling will also become more apparent and the fuel bills can in fact go up.

Resetting the system water temperature according to outdoor temperature will help lower fuel consumption and piping the boiler P/S will protect it from flue gas condensation.

When the time comes for the boiler to be replaced, an accurate heat loss should be performed and the new unit sized accordingly.

Mark H

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LEAD PIPE

maybe they will choke

but coach Green is finaly gone so at least we have a chance now