Viessmann Vitodens-100 F4 Error

yukonliving

Hello everyone,

I hope you can help me, as I am new to the scene with respect to boilers. My wife and I live in Northern Canada, and 2 years ago had a Viessmann Vitodens-100 with a combi installed into our house. It is powered off of a large propane tank, with about a 20 foot buried copper pipe to the house. Recently the temperature has been cold in the night (about -25 c or -13 f) but heating up to -5 C or 23 F during the day.

The thing has stopped working, and for the past week or so we have had no hot water. Turning it on or off (both with the reset and at the wall) results in it powering up for a minute before showing an F4 error. It did this while we were away and the temperatures were really cold (-39 C, why do you think we left!) and the same thing was happening.

I had a 'viessmann tech' come and check the boiler and he told me that there were no pressure issues, no gas valve issues, electrodes issue, and that the ionization current is more than good. According to him the F4 error is one that he is rarely able to fix.

I spoke to my contractor who feels that possibly the propane is getting too cold when it is in the ground and as a result the boiler is not burning. He is planning on coming out tomorrow to ensure that there is sufficient propane reaching the boiler.

Does anyone else have any ideas? I have been reading all I can but the internet seems to have very little information on it.

Many thanks

ps- bonus points if you can talk about why the combi does not seem to produce sufficient water to run the shower, and the contractor is now telling me we should put in a hot water tank. I note that this is after telling me that one of the main benefits of the combi was that we would NOT need a hot water tank!

Grallert

If I recall an F4 can be a frozen condensate line causing condensate to back up into the combustion chamber. That affects the ignition or flame quality. Someone else might jump in and correct me.
Bonus points. Can we assume the installer took into account the domestic water flow rate and the incoming water temp? This is a pretty common cause of low water temp with a combi boiler. Some times a buffer tank in the cellar or mechanical room will allow the incoming water to warm a bit so the boiler doesn't have to make up such a big temperature difference.

psb75

If the F4 error code is "lack of ignition" (or some variation of that), I would suspect the very cold temps and lack of LP to the boiler. What is going on with the low pressure regulator? They can freeze up. LP fuel itself can have moisture in it. These are things I have dealt with in Viessmann and other mod/con boilers during deep cold events.
Lack of hot domestic water in combi: is there a preheat function on your plate x-changer? Also make sure your heat x-changer is not limed-up--from hard water.

Zman

Did your tech say anything about checking gas pressure or performing a combustion analysis? If not, it would be time for a new tech. The issue could be with the propane or several other things. Without proper tools, he is just guessing.

For the bonus round, what is the exact model? It looks like the max is 125k/btu input. That is pretty low for demand DHW.

yukonliving

Thanks everyone for the responses!

I actually read another forum talking about a frozen condensate line, but I think this is unlikely as the unit is in my laundry room and the condensate line runs along the inside of the house to the floor of the laundry room (I think, I will confirm this with him).

I don't know where the low pressure regulator is (or if I have one) and will ask him about it. Today I believe that they are coming to measure the pressure of propane and make sure it is flowing. One thought was to hook up a 100 lb tank right at the wall and see if the boiler works, which could mean that the buried line needs to be insulated this summer. From the sounds of your responses this is a distinct possibility.

I have no idea what to do if there is too much moisture in the propane were are buying.

As for the combi- you are all saying things that jive with what my contractor is saying. Having said that it makes no sense to me why they would make such an underpowered unit. The combi can't run a low flow shower with no other water running in the house. Am I alone in thinking this is insane?

Grallert

It should run a shower without a problem unless your water is coming in at 34 degrees I would think.

Robert O'Brien

Is it a B1KA or WB1B?

yukonliving

I think our tap water is about 3 degrees celsius and so that is about 34 F I think.

WB1B

psb75

Oh yes. That 34 F incoming water temp is a problem. That is almost about as low as it can go. It very much de-rates your combi's ability to make sufficient domestic hot water.

LouisFournier

In my experience you should look at the regulator. They make a devise that graphs your incoming gas pressure taken from the inlet side of the boilers gas valve, my hunch is the line is fine from the sounds of your ambient temperature it would freeze and not be able to thaw on its own. 50% of the f4 propane calls i get are low on propane on those really cold days. Im in Portland Me we do get down to -15 on occasion

GW

We had a Bosch locking out with a general code. After many trips we finally talked the home owner into getting the propane co to change the 2nd stage regulator. Never heard back.

As mentioned check the condensation drain, if that can drain freely you will have issues

Your heating guy is learning on the fly I see. That water heating story was fabulous

GW

Wow 34 f someone didn’t bury your water main very deep

yukonliving

It's well water and we're in Alaska. I think that's about what is normal up here.

What type of second stage regulator would you recommend? It does seem to be when it is cold that we have the most trouble.

Also, could this have anything to do with the air intake? It is a short chimney, does it matter that very cold air is coming into the boiler? I would think that would actually be better, but just thought i would ask

yukonliving

ok i lied. I measured and it is 48 f

GW

I’m not an LP guy but know the basics. I think it’s either guess that’s it’s sticking, guess that’s there’s moisture in the tank, or get some sort of data logger on there to prove it. The problem may not show its ugly head when the LP tech comes, not that he cares anyway LOL. (Just sharing my experiences)

Ok well water wow that’s cold. And the plumber didn’t know this? Did he just arrive in town from some other climate? The manufacturers have specs on GPM and certain temp rises