Questions about Simple Storage Sticky

[hiker88]

Hi everyone,

I joined the forum late last fall after lurking most of the spring and summer. Well as this spring comes on, I'm getting real close to starting my own boiler project.

Next Tuesday, the company I'll be getting my boiler through is coming out for what will probably be the last visit before I buy the boiler. I've read the simple pressurized storage sticky a few times and the scenarios described and how things should work really seem to make sense. My setup will be slightly different however, so I want to make sure things still apply. Basically, I'm going to show the sticky to the installer and say "I want mine to work like this".

So my setup will be with unpressurized storage and I do not have an indirect hot water heater at this time. My guess (and what I'm hoping people will say) is buy an IDW and everything else should apply.

Otherwise I don't understand how I can handle the no fire, cold storage, call for heat scenario. If I leave my aquastat as it is now, the boiler will cycle off and on all day to maintain the boiler temp even if there isn't a call for heat. Also, if there was a call for heat and storage was cold, I wouldn't want my boiler trying to heat up 820 gallons of water...

Before I knew about gassification wood boilers, and I was trying to look into ways to cut down on oil, I had the oil company out here and they said my boiler could be programmed for "cold start" with an IDW.

Please let me know what you think.

 

[hiker88]

A couple minutes after posting this I got thinking how the storage tank has a coil for DHW. So, I guess I'm a little confused how to configure the oil burner properly for backup.

 

[Onfoot]

A couple minutes after posting this I got thinking how the storage tank has a coil for DHW. So, I guess I'm a little confused how to configure the oil burner properly for backup.

There are lots of guys on the forum who can fill you in on all the technical possibilities, but FYI, my system consists of a Tarm Solo Plus 40 wood gasifier boiler and a Viessman oil boiler (cannot recall model as I type this), both linked to my 850 gallon non-pressurized heatsink. There is a thermostat switch in the heatsink that calls for heat from the oil boiler (which also heats the heatsink) if the heatsink temp drops to 112F. The oil boiler will then cycle on until the heat sink is about 120F. The house draws all DHW and radiant heat from the heatsink. My goal with my Tarm is to prevent the heatsink from dropping to 112F.

I did not do the install, it being beyond my expertise, but the system is plumbed to prevent cold water shock to either boiler.

The system has worked very well, this being its 9th winter. In effect, my heating solution is to be transferring BTUs from wood or, if necessary, from oil, to my heatsink, all the house hot water needs being provided by the heatsink.

Not sure how helpful that is, but FYI.

Barrett (aka Onfoot)

 

[hiker88]

No, I think that is exactly what I was looking to hear. So it seems the oil burner only heats to 120, that's the part I don't think I was making the connection on. I was imagining the oil burner kicking on and trying to get the heat sink up to 190f or so. Scary thought.

I'll have to study those schematics some more and really ask some questions when he is here next week.

 

[Onfoot]

It would indeed be scary for the oil boiler to bring the heatsink up to 190F! And totally unnecessary. In the summer, I depend on the solar array to keep the heatsink above 112F. My only concern at this point is that, having added an additional 1200 sq. ft. of heated living space, my Tarm is unable to get enough BTUs into the heatsink on one load of wood to prevent the oil boiler from needing to kick in before I get home from work or, sometimes, before getting up in the morning. So I am looking at a larger capacity boiler and a larger heatsink this summer. Good luck with your install!

 

[henfruit]

Hiker, Is the company you are buying the boiler from able to supply you with drawings to plumb the boiler for proper pipe size and pump size and how to wire it so it all works toghther with you oil boiler?

 

[ozzie88]

Sounds like your up for this project. I would set up storage for sure. I built my unit and my house is 1000sq. and basement same plus DHW. I have 300 gal. storage and when Temp.s are outside abut say 20-30 daytime and teens night I run boiler one time day.when zero 2 time day and in summer once every 3 to 5 days. It so much better to run unit flat out than have it burn on and off all day & night. My water temps are from 180 to 210 and preasure systom too, Have not had any problems with this set up so far[nock on wood]
With storage the temps stay fairley even, when there call for heat it just draws from all tanks[close loop] Have this unit set to come on at 150* F. and off at 190*, when in cool down rest of heat takes water to 200-210*, Oh, I also have in floor heat in the bathroom workd well, Hope this may help ask what you want..

 

[hiker88]

Hiker, Is the company you are buying the boiler from able to supply you with drawings to plumb the boiler for proper pipe size and pump size and how to wire it so it all works toghther with you oil boiler?

Yes they are. I'm just trying to educate myself a bit better so that I fully understand the capabilities of the system. I want to make sure that my system will have the same functionality as in the simple pressurized sticky because that really makes sense. I'd like to be able to ask them some detailed questions about operation when they come out again.

I had an independent energy audit a couple weeks ago and my heat load is approx. 38kbtuhour. I'm going with a 30kw boiler that is rated at about 102,000 btuhr. Originally, the heating company eyeballed the house and thought the 30kw boiler with 650 gallons of storage would be good. I'm actually interested in an 820 gallon tank though, so I am going to run that by them on Tuesday.

The weak point of my system will be the baseboard heat. I've been doing some playing around over the winter though, and my house will warm up (although not very fast) with the oil aquastat turned down to 130 low level and 150 high level. My hope is that with a fire the house will warm up real fast because I should have at least 180 f water (I never turn set the oil aquastat higher than 160-180, and my house heats up fast.) Then, with the house warmed up, I hope the storage will maintain temps reasonably well.

It is what it is I suppose. At least I won't be burning oil. My attic is R30 according to the audit. I'm going to seal all the wiring holes that go up into the attic space and then blow in 10 inches of insulation which will supposedly bring me up to r66. The rest of the house is pretty good; walls indicated no need for more insulation and the blower test indicated .33 air exchanges per hour (goal is .35). After that I will probably slowly start exchanging base board for panel radiators if I find I need to stretch the storage more.

I know that's a lot of info I just dropped. As I get closer to doing this, I really appreciate any feedback.

Thanks!

 

[henfruit]

I would try to keep your storage above 150 during the real cold weather.With the boiler running your base board will recive the hottest water from the top of the tank.

 

[woodsmaster]

I'd definitly go with the bigger tank If it will fit for you, especally with the baseboard heat. That will give you some more time
between fires.

 

[RobC]

I would 2nd any reasonable up-sizing that you can afford either price or space wise. Especially storage.
Over the years I have had 2 marginal systems. Once up and running you usually have to learn to live with it.
There is a wealth of knowledgeable & helpful guys on this forum. A great resource for before installation questions, like you doing. Most, like myself, stumble on Hearth trying to sort out problems.... LOL !
The best is not being tied to the oil or propane guy.....
Cheers Rob