Viessmann Vitodens 200W - Propane usage high

mike1234

Hi,

I just moved into a new home and realized a couple months ago I’m going through propane extremely fast (5-10 gallons a day) when keeping the thermostat set at 62-63F during the day and drop to 60F at night. The propane is used for heating/hotwater and cooking. When I was just using it for hot water, the propane usage was manageable, but once I started using the heat, I go through it extremely fast. I have three zones in my home (two on the first floor and a third zone on the second floor). I’m only using one of the zones, which heats the main area of the house.

I have a Viessmann Vitodens 200W system. Just a few days ago, the company who typically serviced the heating system at my home added a Taco ZVC405 valve control system, which they thought might help with the issue. It unfortunately, didn’t make a difference.

The boiler is currently set at (all in Fahrenheit) Room temp Setpoint 70, Red. Room temp setpoint: 61, Heating Curve 0.6, Shift 40k, Outdoor temp 36, Boiler 163, and Flue Gas 126.

I’m still trying to wrap my head around the meaning of the room temp setpoint, it’s currently set at 70 but my thermostat is set at 62, does it possibly mean energy is being wasted somewhere? I’d like to keep the house warmer, but I’m worried how it’ll affect my propane usage.

Any help or advice would be greatly appreciated

Thanks,
Mike

Jamie Hall

5 gallons of LP per day is around 20,000 BTUh heating load. Which, depending on where you are located and the size of the house, might be quite reasonable, even at your relatively low temperatures.

Before you shoot the messenger -- the LP use and the boiler -- it would be well to figure out just how much heat it does take to heat the structure...

Paul Pollets

Something is very wrong. First, I presume you have radiant heat in an embedded application? A curve of .6 would be useable. Second, take the Shift off and set to "0". You'll probably have to find a Viessmann trained tech locally. I presume you have a low loss header, but post some pics of your system and "near boiler" piping

GW

Question- you're 100% sure you want to point the fuel issues on the boiler? Just curious. What general reasons do you have as a comparison? How big and how old is your home? You're not losing heat? Perhaps your heating system isn't ideal? Do you have baseboard heating (we type bb)? What state are you in? If your heating system is lame (furniture parked up against the bb units is one classic example), the hatch or stair to the attic is ajar, basement door is ope, open or leaking air into the basement, and a dozen other small examples, you're gonna drum up a yuge heating bill.

New Taco---not sure how that would have any affect on this topic. Please tell me why they did this.

163 boiler temp at 36 outdoor---seems too high. 40k seems very high. If you're on bb heat i normally try 29k with 1 to 1.2 slope. here's the deal---the lower the temp the better. But- when you get 'too low', the house will not heat up. That's not necessarily the boilers fault!

Also, you're double dipping the system- you have set back thermostats (and) you have day and night settings on your boiler----choose one!

JUGHNE

Do you have any tubing buried in concrete?
Is your water fill valve always turned on?
Is it possible water leaking under concrete and fill valve adding cold water continuously?

PerryHolzman

The amount of heat it takes to heat your house... IS the amount of heat it takes to heat your house. While the boiler may not be set up idealy. It's very unlikely that its sending a lot of excess heat up the stack - and that the heat is indeed going into your house.

Lets start with some basics. Slant Fin has on their site a downloadable application used to size various kinds of hydronic radiators. It will tell you fairly accurately how much heat your house actually needs (often within 15%). It takes some time to measure all the rooms and input the data. But, it will give you a good understanding of how much fuel usage you should be using - and the size boiler you should have; regardless of what kind of radiators or in-slab/underfloor tubing (etc) you have.

Perry

mike1234

@Paul I’m not sure. The prior homeowner was planning to do Radiant heating, but never went forward with it. Attached is a Pic, please let me know if you need to see anything closer.

@GW – My only indication is that the propane drops substantially when I’m actively using the heat in the house. The house was built in 2003 and is close to 3000 sq/ft and I do have bb in Massachusetts.
It’s what the hvac company suggested we try. They mentioned
the hot water was going to all three air handlers all the time even when they weren’t calling heat, so the idea was it would only send water when heat was called.
Thanks for the advice, I’ll adjust that.

I’d prefer to just use my programable thermostats, but I’m not sure how to just use them?

@Jughne, I’m not sure? I don’t believe so.

Thanks for everyone's help so far!

PerryHolzman

Also, please tell us if there have been recent changes to your heating system or your house (example, installation of a new boiler or an addition).

Perry

GW

Mike ok makes more sense now.

Running boiler water to the coils 24/7--wow that's lame- good to hear that got corrected. That certainly sucked some fuel, fer sure.

You have bb, and you have 3 coils, and it seems like you have radiant? What's with the mixing station? I see that the valves are off.

Coils--that explain why the numbers were jacked up. Coils need-want hotter water or the home doesn't feel as cozy (blowing air that isn't 'warm').

Ducted system(s)- perhaps the air handler systems are deserving of a little scrutiny. If the ducts are losing heat or sucking some cold air, your LP tanks will not be happy.

Question- any icicles or ice dams?

@Jughne, probably not relevant in this case.

mike1234

@Perry – I just moved into the home so this is what I’m starting with. The only change thus far was the work I had done.

@GW – Very lame, when I heard about it! The prior homeowner was going to run radiant heating throughout the house, but never came around to it. I have boxes stacked in my basement with the parts, but it was never installed.

Good to know about the coils and ducted systems. I have noticed that when the heat first kicks on, it takes close to 10 minutes before I feel hot air coming from the vents.

I’m sorry, but what are icicles or ice dams in the context you’re asking about?

Thank you all

GW

Do you have this? 

GW

Also- not super good that it takes 10 minutes for the air to feel warm. You’re wasting a little bit of energy in that scenario. You would save some fuel and be more comfortable if you can get the heating guys to come back and install strap-on aquastat’s, disallowing the blower to come on until the coil is nice and warm.

PerryHolzman

What's the chance that you can finish the radiant heating?

That's usually either tube installed in or under the floors (and that tubing may already be installed - awaiting connection), or radiant wall or ceiling panels (which again may be already installed - or perhaps stored in your basement).

That would likely eliminate the air handlers...

It also may not be real cheap to finish the installation. But, I believe its a fair question.

Perry

GW

Also! you're boiler wasn't well-suited for the type of system you have. I presume your boiler is keeping heat going 24-7. That boiler (you have the 2nd generation 200 series, we are now on the 3rd gen) was more designed for 'constant circulation', in other words, heating is always on. So, you're wasting some fuel. here's a test---turn all your stats down or off, make sure the water heater doesn't fire up too. Grab a cup of hot coco and sit in front of the boiler. Does the boiler still fire? YES? then you're wasting some fuel.

There's a way to make the boiler fire 'on demand' so to speak, but i have forgotten the steps and would have to dig my head into the manual. Other Viessmann guys here on the sire might chime in. If you can get your air handlers to kick on the boiler instead of the outdoor sensor licking on the boiler, you'll save some fuel.

Now, IF you even get the radiant heating going, then we are getting back to what this boiler was originally designed for.

@Paul Pollets you recall how to make the 200 b series do a set point demand?

The 3rd gen 200 series is total cake, but you don't want to buy a new boiler i presume.

bburd

For a 3000 square-foot house in Massachusetts, even if the house is relatively modern and thermostats set low, the propane usage sounds reasonable at this time of year. 

mike1234

@GW – No I don’t have them on my house. Good info about the strap-on aquastats, I’ll be sure to mention it

I’ll try to do that test sometime today, but I seem to recall the boiler firing pretty frequently even when the heat wasn’t kicking on or the water being used.

I do think having the boiler fire on demand would make a lot more sense, then constantly firing.

Haha no, I don’t have the appetite for that right now.

@Perry – I don’t think I’ll be finishing the radiant heating this year, maybe some time down the road.

sunlight33

From the picture he posted, I believe that's a 3rd gen 200-W, you are talking about the B2HB series, right?

sunlight33

GW said:

There's a way to make the boiler fire 'on demand' so to speak,

Are you talking about using Vitotrol 300 as a indoor temperature feedback?

mike1234

@sunlight33 - listed on the side, the model is a B2HB 45

sunlight33

mike1234 said:

@sunlight33 - listed on the side, the model is a B2HB 45

Thanks. How many times does the boiler cycle per day?

GW

well well my mistake! Don't know how i jumped to a b series. In that case, you may be good to go. All depends on now the original guy set it up.

We did our first B2HB two years ago---no one ever sent me a memo saying the B2HBs could take a demand call (without going into a deep dive like the Wb2B series). I truly don't want to get into a deep Viessmann conversation, trying to keep things real

Mike is your heating guy pretty good? He can tell you if you're set up for ZC1 or HC1 set up. You want ZC1, NOT HC1 for air handlers/coils. (ZC is zone control, HC1 is heating circuit 1), the earlier B2HB was not easily set to do ZC1---there was a song and dance on how to do it, (that was our first B2HB, evidently I got 'old stock' 2 years ago). Now I can set up V's w-o looking at the manual, cake.

GW

@sunlight33 not was I was thinking---we only dig those wall units when we are looking for constant circulation- like a bigger cast iron job/radiant job. This job needs more simple than more complex.

GW

also- 45kw boiler---kinda big for a modern 3000 sq ft home. I have a WB1B-26 series 94000 BTU, my home is about 2800 sq ft (very well sealed and insulated though) and it still cycles badly. I bought a buffer tank, just don't have the energy to yank it apart and install it. I may just do it when i change the boiler out down the road.

mike1234

@sunlight33 I'm not entirely sure. When you say cycle, are you referring to the boiler firing?

@GW under information on my boiler it says heating circuit 1

sunlight33

mike1234 said:

@sunlight33 I'm not entirely sure. When you say cycle, are you referring to the boiler firing?

Yes

GW

he mentioned the air handlers were getting full time hot water from the boiler- I suspect it’s cycling badly. Time to get a good viessmann guy in there to whip things into shape

sunlight33

GW said:

also- 45kw boiler---kinda big for a modern 3000 sq ft home. I have a WB1B-26 series 94000 BTU, my home is about 2800 sq ft (very well sealed and insulated though) and it still cycles badly. I bought a buffer tank, just don't have the energy to yank it apart and install it. I may just do it when i change the boiler out down the road.

the 45 is 60-160 MBH, your 26 is 31-94 MBH, which means even at the lowest modulation it will put out twice the amount of heat, so I am concerned about short cycling.

GW

Yes- 3 issues at hand:

No mass in this system, just coils 
Boiler is way too big
Boiler seems to be running off of Heating Circuit 1, not Zone Circuit 1 


 

mike1234

@GW & @sunlight33 - Thank you very much for the information. Based on what you're saying, the best next course of action would be to bring in a Viessmann expert to take a look at the system?

sunlight33

Yes I think you should. There are manuals available online for setting up zone circuit but you should get someone who's familiar with your boiler model to look at it.

mike1234

Thank you very much for the recommendation @sunlight33 . Just to satisfy my curiosity, what's the main advantage of having it run as a zone circuit vs. heating circuit?

sunlight33

Correct me if I am wrong, I think in zone circuit you can wire the thermostat into the boiler so that it can support different temperatures for each zone.