Downsizing nozzle on wtgo-4 and riello f5

Swilson08 · September 18

I have my service tech scheduled for a annual maintenance in two weeks and looking for some advice. I currently have a 2005 well-mcclain wtgo-4 without a tankless coil and a riello 40 f5 burner.

I have a 2800square foot house with a attached unheated garage. This is a split level/raised range style. 2 floors. 1st floor sits on a slab. Garage may get heated one day after it's insulated. The square footage is from wall to wall I did not measure each room individual.

I have three zones. Two for heating and one for a well-mcclain 29 gallon indirect water heater. One zone is 74 feet of baseboard on 2nd floor and the other is 52 feet of baseboard on first floor. This give me roughly 63,000 btu of baseboard. Currently the wtgo-4 is speced out to have a 1.20 nozzel. The btu rating seems to be a lot more then we need. Do you think it's possible to bring it down to the wgo-4 spec of 1.0 nozzel or even smaller.

Figured I would ask the pros on this matter. Thank you in advance for the help.

Jamie Hall · September 18

I think I've said this before... for hot water heating, the boiler should be sized on the basis of what the heat loss for the structure is. So... before you start thinking about possibly down firing that burner -- if it's even possible with the burner and boiler combination -- do a heat loss on the house.

Swilson08 · September 18

@Jamie Hall thank you for the feed back. I'll work on the heat loss calculation on the house tomorrow and get back to you.

STEVEusaPA · September 18

Don’t down fire it, especially without a full combustion analysis.
The burner is almost always the most efficient based on manufacturer testing and recommendation.
A smaller nozzle might be unstable in an F5. Lower flame temperature can cause too low a flue temperature causing condensing...which causes a number of problems.
Any money you think you’ll save will be wasted via poorer efficiency.
Your boiler is very oversized. Only a properly sized boiler based on a proper heat loss will provide the best opportunity for savings.

Swilson08 · September 18

@STEVEusaPA thank you for your thoughts. I understand combustion analysis needs to be performed and that is why I am asking now since I have a service tech scheduled for a annual pm in two weeks. I will work on the heat loss calculation this week. Improvements in insulation and windows have been happening slowly over time. The reason I ask about downsizing to the 1.0 nozzel is because it is in some of well McLain and riello data books for my boiler and burner setup. I know my boiler seems to be way oversized. Unfortunately I bought the house like this 4 years ago so working on getting things worked out. 1972 house with a 2005 boiler. I have attached two documents one from well-mcclain and the other from riello manual. Ideally I would be swapping with a energy Kinects or a burderous but not sure of that's in the budget right now.

HVACNUT · September 18

It shows a 1.00 GPH input as an option to downfire. That's not the nozzle size, but firing rate. A .85 nozzle is used with adjusted pump pressure to achieve 1.00 GPH.
I never really understood the 3 and 4 section WGO. They are basically the same boiler, dimension wise. The 3 section has a wide middle section that's substituted for two sections to make 4. The 3 actually holds 1.5 gallons more water than the 4 section.

STEVEusaPA · September 18

Yes but your chart doesn't show it being downfired. It has a smaller nozzle and increased pump pressure maintaining the same firing rate (and needed for flame stability).

Which is still a better set up and recommended over the 1.20 and 100psi setting.

Just note the change in the pump pressure, air shutter and turbulator. If you don't change all 3 (check, verify with gauges, smoke gun and analyzer) you'll have problems.

Nozzle, not nozzel. Doesn't your spell check let you know?

Another guy on this site spells it that way too.

Swilson08 · September 18

Thank you all for some advice. Let me do the heat loss calculations and then get back to you with what you think would be the best plan of action. Well technically the best plan would be to replace the boiler but that's a whole other topic. I want to narrow a plan down for nozzle size so I can make sure the tech coming can adjust everything as needed and verify the results with me. New service company so it will be a good test to see how they perform. I have no problem doing the work myself, I come from a Diesel engine/turbine background but just don't have all the testing equipment to do it all. If it was me I'd be testing all day with different setups to find the best results but that's not going to happen. Just trying to squeeze the most of it this boiler of possible. Burned about 800 gallons in a year of b20.

Thanks again for all your help.

Swilson08 · September 18

@HVACNUT so even though the wtgo-3 and 4 are almost identical would you say downsizing to the wtgo-3 spec would be out of the question?

STEVEusaPA · September 18

I wouldn't waste any time with a heatloss until you're sizing a new boiler.
800 gallons for the year? What's your city/state? I could give you a pretty fast/accurate heatloss.
The smallest boiler will still be too big, and downfiring won't help your situation, nor save you any money, but it may create problems like I mentioned above.
Save your money for an EK or smallest triple pass.

Swilson08 · September 18

@STEVEusaPA I am in Seaford NY. Thanks for the info.

STEVEusaPA · September 18

Your heat loss is approximately 37000 btu's.

Swilson08 · September 18

@STEVEusaPA what size boiler would you recommend then?

STEVEusaPA · September 18

If the heat loss is actually 37000, then 37000 BTU...LOL..
However you won't find much smaller than 60k in oil, maybe add a buffer tank.
Another option is to go with an Energy Kinetics, which isn't smaller but different technology.

Swilson08 · September 18

@STEVEusaPA thanks. I find that it's amazing how small a boiler you actually need. And how much bigger my current setup is. I have gas on the block so that's a option. Well if NY approves the new pipe line so they can provide new customers with gas. Only if the electric boilers didn't draw so much darn power. EK will only sell it with a approved installer doing the install. So that raises the cost of install.

STEVEusaPA · September 19

Ek's are more expensive than a conventional boiler, but worth every penny. There really isn’t any reason the install costs should be higher.

Swilson08 · September 19

@STEVEusaPA it seems that EK would be an ideal system to make separate zones for rooms.

Right now my 2nd floor zone is 74 feet of basboard with a total 3/4 copper run of 124 feet. My issue currently is the flow hits the bedrooms first and hits the living room last which results in hot bedrooms and cool living room. My plan was to reverse the flow so it hits the living room first then the bedrooms. But then I thought of just splitting it into two zones. One for living room dinning room and one for the bedroom and bathroom. But since my boiler is way oversized this might be an issue.

HVACNUT · September 19

> @Swilson08 said:
> @HVACNUT so even though the wtgo-3 and 4 are almost identical would you say downsizing to the wtgo-3 spec would be out of the question?

The firing rate on the 3 is .95 GPH. Only .05 less than the downfire 4 section. Yes, out the the question.

Swilson08 · September 20

Thank your all. I appreciate all the help. I'll stick with what I have now until I can afford to swap it out. Preferably before it goes down. Might need a new tank as well. I believe it's original to the house. Oil company doing a ultrasound sound on it in two week so I'll know then. I'll have the tech set it up for the 1.0 nozzle specs in the book for that unit.

HVACNUT · September 20

Weil McLain does offer a WGO-2. Not that I recommend it.

rick in Alaska · September 21

Personally I would buy a WGO 2 for a lot of the jobs I have. I have only seen one in the state, which I put it in my neighbors house. It runs great, but is still oversized, but at least it is not way oversized like anything else I can buy. I was told they won't sell it in Alaska because we won't buy it because it is too small. I haven't found an oil boiler yet that is small enough for 95% of the jobs around here.
Rick

HVACNUT · September 21

> @rick in Alaska said:
> Personally I would buy a WGO 2 for a lot of the jobs I have. I have only seen one in the state, which I put it in my neighbors house. It runs great, but is still oversized, but at least it is not way oversized like anything else I can buy. I was told they won't sell it in Alaska because we won't buy it because it is too small. I haven't found an oil boiler yet that is small enough for 95% of the jobs around here.
> Rick

You are right of course. But pin HX boilers in general are not on my list of recommendations. I would go with something like a Buderus G115-3 piped P/S. This coming from a guy who has a WGO- 3 in the basement.

Swilson08 · September 22

@HVACNUT I've always like the buderus. What do you mean pipped p/s. I do like there indirect that has a access hatch for cleaning the coils and tank.

Swilson08 · October 8

Just figured I'd give you all a update. Service tech came in did a annual service on it. Boiler was super clean he stated. Nozzle was a .85 so he installed a .85 60 A nozzle back in it. Draft was 2 at fire and 3 in flue. CO was 9.4 efficiency was 84 and stack temp 430. He did not make any adjustments because he said everything is running well.
It ran for a few days then had trouble starting so I had them come out again and they had to make a air adjust on the riello and then it fired normally again.

Downsizing nozzle on wtgo-4 and riello f5

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