Replacing oil with gas... WM or Viess???

GW

Those questions mean you should be calling a pro! Don't be a hero and screw eveything up; you'll spend more in the end. This trade isn't that easy!! best of luck, Gary

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Dave_4

Oil to gas... long...

I just bought a 1250 sq ft two floor cape in sw CT. Ancient 165k btu New Yorker with dhw coil (at least it has a mixing valve), Taco 007 circulating a diverter tee system with cast iron radiators. Heat loss will be 56,000 with new windows, probably much higher now. It actually works pretty well, even in this cold weather.

I'll be adding two bathrooms upstairs most likely with towel warmer radiators and adding a cast iron radiator from downstairs to the larger upstairs bedroom. I'll be removing the cast radiation downstairs to staple up Onix for the entire first floor.

I've been cruising and lurking heating sites for a few weeks learning all I can about system upgrades, and here's what I figure... We'll be adding gas service to the house, so we'll spring for a mod/con boiler. It will save a lot of space (losing the oil tank) and I LOVE the idea of circulating water through the system at just the right temp. Our current house uses oil fired single zone d-tee setup with cast radiators that short cycles and over heats the rooms.

I've narrowed it down the the WM Ultra105 or the Vitodens200 6-24. I'll use an indirect dhw tank with either one. The Vito looks remarkably simple to set up, with an integral variable speed pump that I should be able to just reconnect to the current loop. (I'll wait to do the first floor radiant later this summer). The literature seems very finicky about flow rate though.

I'd have to add a pump to the WM, but it seems pretty simple too, with built in controllers for heat and dhw. When I dissassemble the d-tee setup, I guess the best way to pipe the cast rads and the Onix loops is through a manifold setup. That's today's best alternative to a d-tee system, right? I'll control the whole house on one zone. The Onix and cast rads should be around the same temp 150 degrees, somewhat simplifying the setup, I think.

Will I need a seperate manifold branch for each cast radiator? Or can I connect the two bath and two bedroom rads together in series?

Am I on the right track here? Or am I getting too complicated? I'm leaning to the WM for local servicability and price, but man, the Vito looks easy to set up. I'll do most of the work myself and TRY to find a local contractor to help with the start up. Very few local guys want to get involved in a project like this, and I've been getting nuicance bids.

Thanks in advance for your help,

Jason

Am I on the right

clammy

vissemann

If you have the coin go for the vissemann ,but before you go yanking out those cast rads do yourself a favor and do a proper heat lose and then check and run a radiant tubing program to see if you can in deed heat your home with radiant with out a secondary heat source and also check to see how over sized your current rads are you might be surprised about how low a water temp you could heat your home with using standing cast iron rads ,also take a look at using pex with plates for your staple up it's a bit rougher to install on a retro fit but the lower operating temp and good out put pays off in better comfort .If the original mono flow system is in good shape i would leave it install a some trv and a pdv on that loop and do a home run system for your second floor using panel rads sized for lower water temp .Using lower water temps will give you the most out of a modulating condensing boiler like a vissemannn plus they have some great plug and play stuff as for controls and electronic mixing valves .peace and good luck clammy

Mad Dog_2

Look at the Buderus GB 142 as well

Very well built and affordabale. That heatloss sounds high for a building that small. Double check it. Mad Dog

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Dave_4

I'll be keeping the cast rads on the second floor and adding towel warmers. On the first floor, floor space is an issue, and the flooring nails through the subfloor preclude me from using pex and plates.

Am I correct that the cast radiators on the second floor will respond well to the 150 degree temp used in the Onix? Will that enable me to run the whole system on the same temp with a single zone and manifold?

Also, should I home run each cast rad on the second floor to it's own outlet on the manifold? Will the variable speed pump on the Vitodens handle the complete system?

The heat loss was done twice and came out 52k and 55k, so I'm reasonably confident that I'll be ok.

Thanks again,

Jason

GW

I'd go with the Vito. Are you gonna hire someone to do this? It's not rocket science, but not exactly a system to chomp your teeth on either.

Sharing two rads on one line? I've bull-headed these and fed both parallel, return the same way. Just purge one at a time to confirm flow.

share some pics when you're done, we all dig some good boiler room pics, especially the wall hung stuff.

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McKern

Have you considered the Prestige?

A Prestige would actually be by far your best bet. It seems like it is the only boiler that's well suited for what you are doing. You need the boiler now, you need the other stuff piped when you get ready to do it - sometime in the future. You aren't ready now and you should try and break things down into simple sections.

Okay so phase one. You stick the Prestige onto your monoflo system. Maybe even right where your boiler was except you'll be hanging it on a bit less than 20" of wall. You can pipe it direct. I'm completely confident that the built-in Grundfos would have an ideal speed. Actually speed 2 is a pretty sure bet unless your monoflo system is really small, then speed 1. Anyway, pipe it in and you're good to go. Your electrical consumption will be about 100 watts, 14 watts on standby. Direct piping is supported and encouraged by the mfr.

You can change it to P/S piping once you're ready. Then you'd set the internal pump to speed 1. With another 15-58 on speed 2, you're still at 150watts. Or $10 a month if continuous at 10 cents per kWh.

You also would never have to worry about cleaning the heat exchanger. It is self-cleaning. The heat exchanger is also wide open with a 2.5 gallon capacity. The boiler can fire with the circ off and will do so for frost protection.

It uses the same control as the Ultra, which is also the same as the 95M-200, the Burnham CHG, the Cleaver Brooks Clearfire series. There should be lots of supply years down the road. It has 2 built in levels of protection from low water levels.

The boiler doesn't modulate as low as the others, but it would work perfectly fine that way regardless. The domestic hot water recovery would be amazing.

T-T also makes a very good and very well priced indirect.

[Deleted User]

Would you elaborate please Uni R...

...about the Prestige's heat exchanger being self-cleaning. The manual requres that, as part of annual maintenance, the boiler be placed on high fire, then flue temperature is compared with supply water temperature. If the flue is more than 54 degrees F higher than the water, exchanger cleaning is mandated; the manual provides a complete cleaning procedure.

I'm curious how often those who have performed these annual checks find the temperature difference great enough to require cleaning. Or has the "self-cleaning" design kept you from ever needing to? Thanks in advance.

McKern

See \"Cleaning a Prestige\"

This should be a new thread.

scott markle

old cape

The vitodens 200 is a great boiler. Be aware that viessmann vent components (coaxial) are a bit more time consuming than pvc and a lot more expensive. You won't be able to run this this type vent through your existing masonry chimney as you might be able to do with pvc. Viessmann only allows balanced flue venting thru Viessmann coax. pipe. I recently used a gb-142 because client could not stand the look of viessmann vent kit. I liked the gb-142 and on this particular job the ability to use a tekmar tn4 controler made it a better choice in the end. Still it's my impression that the burner technology on the Viessmann is the best available, at least in terms of emissions. I under stand that viessmann is soon to introduce a vitodens 100 which will allow 0-10v control from third party controls (tekmar). As far as your house I recommend keeping the cast iron. Iron works great on outdoor reset. The more radiation you have the lower you can go with your heating curve and the more efficient (more condensation) your vitodens will be. Go ahead with your onix or consider ultra fin. t
These products are a good choice because they are matched well with the iron in terms of temp. If the downstiars currently heats well (ie. ballenced )consider leaving the iron piped as is, no trv's. You will be able to adjust your heating curve to match this new arrangement. You might also consider a indoor sensor with the comfortrole remote. This would fine tune the heating curve and provide more responsive behavior when temperature settings are changed. trv's are cool but if your really want to get the most out of a condensing boiler you want to send return water back as cold as possible. trv's and the requisite differential bypass valve can not accomplish this. It is important that you estimate what your design temp. with the added floor warming will be for the downstairs. This is tricky with old iron because published outputs for these are hard find. The upstairs rads. will need to be sized large enough to heat at what will probably be a fairly low design temp. here home run piping to generously sized steel panel rads with trv's would be a good idea. Prehaps a direct return arangment to the existing mono flow loop upstream of the downstairs rads. with a small circulator and differential by pass valve. Keep me posted. Recent gb-142 photo attached

Jason_29

Thanks everyone for your thoughts and advice. The Prestige seems perfect with its primary setup and plug and play dhw.

I'll follow Uni R's advice and just swap it out, worrying about the Onix later if I decide to do it. Otherwise, I'll keep the cast rads and add flat panels if I need more radiation.

I like the idea of quick domestic hot water recovery. I'll have three bathrooms including a 6 foot jet tub. TT makes a Smart 40 which seems like at 120 degrees dhw would be perfect.

Thanks again,

Jason