Bosch Greenstar Combi 151 not able to keep up

MonikaG

I got a bosch combi unit installed last year. I am having some trouble with it. It is not able to keep up on a cold day. I am wondering if it is related to any of the settings not set correctly. I tried calling the contractor who did the install but, he is not very helpful. Now, he doesn't even pick up my call.

How do i check if all the settings are correct?

Thank you

Monika

bulldoglax

Was this a retrofit?

What kind of radiation

kcopp

What is not keeping up? Hot water or heat?

Ironman

Is it the wall hung or floor model GreenStar? If it's the floor model, do you have the Bosch room sensor which takes the place of a thermostat?

Some pics of the boiler and thermostat would help.

MonikaG

@Hatterasguy..will try that tonight. Thank you.
@ bulldoglax..it is a new unit. I had oil heating earlier. Converted to gas and got this green star combi unit installed
@ kcopp..the thermostat is always showing 4-5 degrees lower than the set temperature. The house is very cold

kcopp

Are you setting the thermostat back at night?

MonikaG

@Hatterasguy the dial was at position 6. I moved it to next position which is the max setting.

MonikaG

Here are pictures of the control panel

Ironman

MonikaG said:

Here are pictures of the control panel

Your pics didn't post

MonikaG

MonikaG

kcopp said:

Are you setting the thermostat back at night?

It is set at 70 all the time.

MonikaG

Ironman said:

Is it the wall hung or floor model GreenStar? If it's the floor model, do you have the Bosch room sensor which takes the place of a thermostat?

Some pics of the boiler and thermostat would help.

The model number is GREENSTAR COMBI FS 151 (KWB42-3).

I posted some pics of the boiler. Will post some more when i get home.

Rabbit02

Also try pushing the Eco button, with button lit the boiler will switch between space heating mode and domestic mode. This prevents the room from cooling off too much. But it also will only allow the boiler to run on DEMAND when domestic water is being drawn. Instead of continually maintaining temperature for domestic water (Comfort Mode= light off). With light off Domestic water heating is priority and heated first then space heating.

Rabbit02

Also the Bosch FS(free standing) unit did not come with an outdoor thermostat but your contractor may have installed it as an option. If it has an outdoor thermostat, take it off. How many thermostats do you have? If you have more than one thermostat, an external circulator should have been installed. The boiler has an internal circulator which is only good for one zone of about 45,000 btus. In addition to external circulator (if you have multiple thermostats) the Low Loss Header needs to be utilized. Its a plunger that is located in the boiler which turns it into primary/secondary piping. Since it is a modulating boiler, if the flow rate(circulation) is not right it wont fire up to its full btu potential.

Robert O'Brien

There is no FW200 control.

GW

it's either a flow issue, an air-bound issue, a boiler temp issue, or one of several more possibilities.

When you say your house can not keep up to what the stat says, when it the boiler temp showing? And, I realize you may not have the means to check the temp of the piping, but does the return feel similarly hot or is it much cooler?

And, when this is happening, does the boiler seem like it's revving a lot or a little?

You may want to take a pic from 8 or 10 feet away so we can see all the piping and zone controls.

Yes if they goofed up the plunger that would be a problem for sure

MonikaG

Hatterasguy said:

MonikaG said:

@Hatterasguy the dial was at position 6. I moved it to next position which is the max setting.

Hopefully, that will be sufficient and the house will be comfortable.

It didn't help. Last 2-3 days have been very cold and I am again having the same issue. The thermostat shows 66-67 when I set it to 71. It shows 70 when I set it to 78. The house feels cold.

MonikaG

GW said:

it's either a flow issue, an air-bound issue, a boiler temp issue, or one of several more possibilities.

When you say your house can not keep up to what the stat says, when it the boiler temp showing? And, I realize you may not have the means to check the temp of the piping, but does the return feel similarly hot or is it much cooler?

And, when this is happening, does the boiler seem like it's revving a lot or a little?

You may want to take a pic from 8 or 10 feet away so we can see all the piping and zone controls.

Yes if they goofed up the plunger that would be a problem for sure

I see 156 on the controller. Is this what you asked?

I had a technician come over and look at it today. He is saying that the unit is short cycling. He needs to do a deep diagnosis and is charging $450 for that. Based on the deep diagnosis, we will no what the problem is. I am so regretting getting this fancy system. I should have stayed with a Burnham system.

Also, he mentioned that the contractor who did the install did not put purge assembly to flush the heat exchange. So, we cannot do maintenance on the unit as the heat exchange cannot be flushed. Adding purge assembly is going to cost additional $575.

GW

Umm seems like no deals there but who am I....the installing company got the majority of the profits so it's not unheard of for the "next" company to charge their full rates.

Something does not make sense, that boiler should be going up to 180 or 190.

I can try to help more but I will need more pics.

Can take a picture from eight or ten feet back.?

Can you pull the front cover off of the boiler and take a picture of that larger black pipe towards the bottom with the knurled looking cap on the end?

albert828

I have the exact same problem that started yesterday. Have you found the solution? It's only a year old.

PatrickHennessy

On a new ZBR 42-3, with indirect water heater, 3131 sq ft house, 3 zones, how many circulators should I need? I have one, my old boiler had two. TIA.

PatrickHennessy

GW said:

Umm seems like no deals there but who am I....the installing company got the majority of the profits so it's not unheard of for the "next" company to charge their full rates.



Something does not make sense, that boiler should be going up to 180 or 190.



I can try to help more but I will need more pics.



Can take a picture from eight or ten feet back.?



Can you pull the front cover off of the boiler and take a picture of that larger black pipe towards the bottom with the knurled looking cap on the end?

I believe the boiler won't heat up to 180 or 190 until the minimum outdoor temp is attained.

Jrthen323

I just install one yesterday and i can get the heat to turn off 

Jrthen323

Wen igo to the thermostat i can hear the clik noise wen its calling bot it seem that the burner stay on  theh got vaseboard heating 

GW

Did you remove the jumper from the tt connection? 

Jrthen323

Yes i did but for some reason the burner stay on

Jrthen323

The thermostat its set to 70 and in the house is 81 and baseboard seem to not cool off wen i turn it off 

GW

Prolly want to start a mew thread. Pull your stat wires off the boiler. What happens?