Weil Mclain SG0-4 Tankless Water Heater

Tankless

Hello, I just purchased a house in New Hampshire and the previous owner just had a new Weil Mclain SG0-4 oil boiler with a tankless water heater installed a few before we moved in. The heating system seems to be running fine. We have very good heat however the system does not seem to be producing enough hot water. We ran the shower for thye first time and it only produced about 4 minutes worth of hot water then went luke warm to cold. I was told that this should be producing much more hot water than this though I'm wondering if there might be an adjustment that I can do to make it produce more. I have installed 2 boilers in the past (with some help) but neither one had a tankless water heater installed. I tried calling the small family company that installed the boiler but I can only leave a message. I'm thinking they are on vacation or something. Any help would be appreciated. Thank you.  

heatpro02920

How hat was that 4 minutes?

Is there a mixing valve on the tankless, it will be near the tankless and have 3 connections, one hot, one cold, and one mix....



What is your aquastat set at? I have seen people turn down their aquastats to save money but then your DHW suffers due to not being able to recover when you put a draw on it... I set most properly sized tankless boilers to 165-185



How hot was the shower, did you get 4 minutes of 160* water and overload the tankless or was it 110* and then slowly went warm?



Also check the shower head, if its a beast than that could be expected, I like to see water saver heads on internal tankless systems...



Was your heat running at the same time, another issue I see is people wake up in the AM, turn their thermostats up and jump in the shower, this can create a low hot water volume problem...



Last thing would be the wrong control, I see this often, make sure your aquastat has a high and low limit, I have seen systems where the people have to run the thermostat to get hot water, then call in the summer because they have no hot water, only to find the wrong control installed all together, easy enough to fix, just need an aquastat in the tankless plate, but still I have seen it numerous times....



If the boiler is relatively new I wouldnt think it would be a scale problem, Im thinking mixing valve or circumstances...

pipeking

yup..

follow heatpro and u will be all set!

Tankless

Thank you

Thank you Heatpro for the very timely responce.

So here is what has happened this afternoon. I called the manufacturer and spoke to very nice woman by the name of Mary. I told her the situation and after looking some things up she said she would need to speak with a technician. So she called me back and said that that unit is designed to produce about 5 minutes worth of hot water given is flow rate and then needs 10 minutes to heat another batch. She did not sound overly confident givin me that explination and I told her that just seemed very surprising and quite useless in a normal size home and she said that I could always buy an indirect water heater. I was mystified. She also told me to make sure that the limit control is set to 180. 

Meanwhile the installation guy called me back and said that it sounds like the water level in the boiler has droped below the full mark and the water is below the coils. So I went and checked and found that it indeed was below the full level so I manually added the water. He said an automatic valve could be added for about $200. He said this just needs to be checked periodically since some of the water is lost due to evaporation. He also said that the aquastat is set to 180 and the mixture valve was set correctly when he was finished.

 The shower was not overly hot just average before going cold and the shower head is a brand new delta water saving head.

The heat in the house was on though I'm not sure if the burner was running.

Your last suggestion heatpro makes me wonder. At first Mary at Weil Mclain said that I should have two setting (high & low) that need to be checked and then when she called me back she that this particular unit ships with a limit control with on one setting and that it should be at 180. After speaking with the installer he also said that there is only one setting and that he set it at 180. Should I be looking to change this. Also is the aquastat the same thing as a limit control?

Thank you again for this very useful information.

heatpro02920

LWCO should have shut it down...

yes the water level being too low will hurt recovery but the low water cut off should shut the boiler off when that happens... See how having the water level up helps, as long as that aquastat is at 180 you should be fine in the summer.... I would not go with an indirect {I dont like them with steam heat}, although you can get an electric water heater and a bronze circulator and use it as a storage tank, this would help and give you electric backup DHW... I have done that a bunch of times..



In my earlier post I was thinking forced hot water not steam, hence the SGO, I don't see steam very often anymore..., my fault.......

pipeking

I DID THE SAME THING

 AS HEATPRO, thought off a hot water system,  i can't remember every model# anymore.lol! but yes try and keep the water level up, and that will help recovery alot. also some tankless coils need a flow restrictor so the water is slowed down going thru the coil to extract more heat.

icesailor

Circular Firing Squads:

I'm dumbstruck about this story. What has happened to Tech Support? Has this site become the DeFacto Tech Support?

Did anyone read the Weil-McLain installation manual for the WGO series boilers? For a WTGO-4 which is the water version of the Steam, SGO-4, it requires a flow control valve. The WTGO-4 requires a 3.75 GPH flow restricter. It needs a properly installed tempering/mixing valve. With a heat trap. The coil is rated a 3.75 GPM with a 100 degree rise. 40 degree inlet cold water to 140 degree hot water coming out.

I'm not a Steamer. But, a steam boiler without a basic fill valve to maintain a minimum water level?

I'm wondering if this boiler was an "A" Block and wasn't a package steam boiler. It sounds like it doesn't have the proper controls installed.

If you want to make it work, make it right. And install a storage tank. You eliminate all the crap of mixers and flow controls.

That boiler, properly wired and controlled with a storage tank will give you all the hot water you will ever want. I know. I've had many.

pipeking

ya, what he said..

NO WAIT.... THATS WHAT I SAID?

BobC

Auto feed

I just wanted to cation you about using a auto water feeder on that steam boiler. They are the work of the devil and to be avoided if possible.



The problem is that they mask problems that can drastically cut the boilers life. You have to know if a boiler starts to lose water because that will destroy the block if it goes unnoticed for a long time.



The waterline has to be checked and maintained at the proper level per the boiler install manual. Anytime you add water to the boiler bring it up to steam so it drives off any oxygen in the water - oxygen in the water rots steam boilers. Start keeping a log and note that date and amount of water you add (inches on the sight glass). If you have to add more than 1/2 inch a month you probably have a small leak somewhere.



You should flush your low water cut off if it is the bowl type every couple of weeks while the boiler is running. Flush water till it runs clean and flush enough once a month to activate the the low water cutoff and (that will shut the boiler down) to be sure it's working. Then slowly fill the boiler to it's normal level and the boiler will restart. Fill it slowly because you don't want to inject a lot of cold water into a hot boiler.



I've lived with steam all my life and never had an auto feed on the boiler, I'm usually in the cellar almost on a daily basis and i check the boiler water level anytime i'm down there. I used to travel for work and I'd leave the house for weeks in the winter, a neighbor would feed the cat and check that the heat was ok. I never had a problem with the boiler and he never saw the water level drop.



Bob

Tankless

Again much appreciated

Well I went back and did some investigating and found that the limit control was not on 180 and in fact is was on 140 so I raised that to 180. However I am having a difficult time getting the water level in the glass cylindar to stay at the water fill line on the boiler housing.

I added water yesturday and brought the water level up but after the system ran I noticed that the water level was well above the line so I drained off some water to bring it back down to the line and just the opposite as before, after the system ran I found that the water was well below the line so I very slowly added water to raise the level and after running once more it was reading about 1/2 inch above the line.

After this period the shower was run and it had plenty enough hot water and seems that it could have ran hot all night. This morning we ran the shower again and it ran flawlwssly, running nice and hot for quite some time never getting cool. Before leaving I looked in the glass and noticed that it is still about 1/2 inch above the line. I notice that when the boiler is running that the water in the glass does fluctuate some. I'm worried that if I drain more water off even if it shows correctly in the glas that after running it will be below the line once again. It seemes to be maintaing around 1/2 above the line and we are getting all the hot water we need. My question is, is this water level dangerous to the system and if so what is the best way to get it right. It has been extremely cold here in NH so I have not been able to shut the system down for long periods since I don't wante frozen pipes. It looks like we are going into somewhat of a heat spell so this may be a good time to do so if I need to.   

Tankless

The SG0

Just as a side note, this unit has the probe type low water cutoff and I notice that it does run a check every now and then. 

Tankless

Just as I thought

I wasn't satisfied leaving the water level 1/2 above the line so i went to the house and drained it down to the line. Guess what happened after a cycle, yup level went down to about 1 1/2" below the line. So after reading some other posts on boiler water level i decided to open up the two black valves at the top and bottom of the glass vile to see what would happen. the level went up a little and i could see a little sediment come down from the top. I then decided to slowly add water back in to bring it up to the line which it is right now with the valves open but i have not cycled the system. My question is do these valves have anything to do with my inability to maintain a consistent water level and second, can the boiler run with these two valves open or are they supposed to be closed.

Tankless

Found some answers

I did some more searching here on this incredible forum and found that the two valves need to be open at all times unless performing maintenance on the glass. OK that’s good to know though I'm not sure why they were closed and it appears they've been that way since installation. Anyway, they are opened now and the water level is exactly at the half way mark and the boiler is shut down. Now that it has cooled a bit I'm going to power it back up and let it run through a cycle and see what happens. Hope the water level doesn’t go down too far.

This thing is brand new and I was excited to have it given that I like how steam heats a home but I had no idea how temperamental these systems can be. I haven’t lost faith yet though.

Tankless

OK good news

Well all looks good at this point. I believe that opening the valves has solved the problem. I set the level and ran the cycle and the level bounced a bit but following the cycle it went back to just where I set it.

I also just got off the phone with the guy who installed it and he said that he has been installing these for 30 years and he knows that when he left it was set correctly. He said that the old lady's grand son who lived there for a short time just before I purchased it liked to tinker with things and must have changed those things.

I am just happy it is now working properly.

Thank you for all your help.