Bio mass boilers

[on31ll]

Thanks guys. These boilers expensive ? Seems the prices for the jobs are outragous

 

[on31ll]

Oh and there is problems with that biomass already. Its not heating the radiators as hot as it should be

 

[Rickster123]

Welcome back on31ll good to see you on here again!

 

[missplumb]

a hack 195 will cost around £40,000 to you if you break it!!!!.
if the boiler has been set up properly then its more likely to be the system at fault than the boiler, but could be buffer temps not set correctly. If you decide to take it on, get the remote set up and i'll have a look remotely for you

 

[SimonG]

You can see the money on the one ive been working on. Its a 90 kw eta, 2000 litre buffer, big valves, big pumps. Looks the business. Sort of stuff I would love to do.

 

[on31ll]

 

[on31ll]

 

[on31ll]

 

[on31ll]

Well the system has the buffers then a heat ex for the heating system. Fire up the hamworthys and boom the system is read hot. Using the biomass it just doesnt reach it. The caretaker has to turn all the pumps off just to get the buffers to 100%

 

[Dotty]

Back end valve is set up wrong. The back end valve on them is a three port and designed to maintain a minimum return temperature of 60-65°

 

[hammers4spanner]

I know absolutely nothing about bio mass so first question is what are buffer tanks??

And second are they installed as badly as what i hear?

 

[Dotty]

Save reinventing the wheel. ...

Buffer Tanks Why They Are Required

And usually, no.

 

[on31ll]

Back end valve is set up wrong. The back end valve on them is a three port and designed to maintain a minimum return temperature of 60-65°

Set up wrong in what way ? How is it rectified ?

 

[on31ll]

The bio mass jobs ive seen have been what i would say look like really good installs

 

[Dotty]

Set up wrong in what way ? How is it rectified ?

In a nutshell, Ryan, you're going to have to sit and watch it.

Check the boiler display to see what the back end temp is set at, 60-65° say, under that temp the three port should be bypassing the buffer, at that temp and above it should be sending the heat to the buffer.

I had a Gilles with the same problem last year. The valve, when I took the head off, had no discernible markings as to where it was. Took me a day to get it right. Eventually found and downloaded the mi's for the valve.

 

[on31ll]

The only thing i can fault on this install is the fact the pumps are on 24/7 fr the cost of install you would think they would of sorted that. And because the pumps are on 24/7 the buffer doesnt get the buffers to temp.

 

[missplumb]

For a 200 kw boiler, the buffers are piped up wrong, as they should be tee'd together to allow even distribution of heat to the buffers. This relates to the thread in the renewable section about buffers with 2 ports or 4

 

[on31ll]

That thread was confusing. Hahah

Stupid question i understand the reason for buffers etc but this system is in a big block of a school. Big heating system etc. so couldnt the boiler be linked directly to the heating and have a lower set temp before the boiler kicks in again ?

Ive been the that building again today. At the plate heat ex the flow is hot and the return is stone cold. To me seems like its undersized.

That biomass is just linked to the the buffers then from that pipework to a heat ex.

So whats the point in the buffers on that system ? Its like 3 curcuits to do one job.

 

[Dotty]

That thread was confusing. Hahah

Stupid question i understand the reason for buffers etc but this system is in a big block of a school. Big heating system etc. so couldnt the boiler be linked directly to the heating and have a lower set temp before the boiler kicks in again ?

Ive been the that building again today. At the plate heat ex the flow is hot and the return is stone cold. To me seems like its undersized.

That biomass is just linked to the the buffers then from that pipework to a heat ex.

So whats the point in the buffers on that system ? Its like 3 curcuits to do one job.

There's link I posted up earlier, Ryan. Explains the need for a buffer beautifully.

 

[on31ll]

I had a look through. What im saying is since there is nothing else other than heating circuit it seems silly

But thats how these systems work i guess. All i know is that its not working now. Gets the buffers upto temp but the heating isnt asmuch

 

[missplumb]

The boiler needs to have a return temperature of 60 degrees minimum for the boiler to work efficiently and not be damaged due to condensation in the boiler flue. The 200kw boilers can take upto an hour to get upto temp hence the back end mixing valve Croppie is on about. Whilst the boiler is warming up, the heating system takes it heat from the buffers so they are there to cover the heat load whilst the boiler can't.
Hope this makes a bit of sense

 

[missplumb]

Is it a new build school, if it's old it may well be undersized.

 

[on31ll]

Well i suggested undersized and the company that installed it swears it isnt. Old bulding of a school. Cast iron rads and alot of rooms have the in ceiling heating where its just one pipe back and fourth.

The system it took over was 6 hamworthys i cant think off top of my head what kw they are but guess at 60 and that equals 360kw.

The system now is installed and has the two buffers. Then coming from the buffers theres a very smal amount of pipework and a pump with a heat ex connecting into the original boilers. If we isolate the biomass and fire up the hamworthys the heating system is perfect.

So either the boiler is undersized or theres a problem.

 

[on31ll]

Just a thought whats the rule of thumb with a heat exchanger ? How do you calculate the size ?

 

[missplumb]

well the plate exchanger needs to be able to transfer the amount of load you have so if your school needs 300kw then thats what size plate you put in, there is more to specifying the plate such as required temps, resistances through the plate etc, but ultimately it wants to transfer the full load also depends on how fast you want the system to heat up. could you do a quick sketch as to the pipework layout from boiler to plate. Is there a heat meter (for rhi, could use this to see what the flowrate is)
for a 200kw ETA Hack boiler, they suggest the buffers are connected symetrically as it uses the heat uniformly.