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We don't use the built in controllers as most of our systems are district heating pumped from a remote plant room to PEX so temperature control becomes a bit more awkward
No, it generally leaves the plantroom at about 80 and according to the rehau rep, the pipe can easily cope with them temps fire the duration. I don't see the point in heating the buffers up and then cooling it before it leaves
The reason for different temperatures is to operate all parts of the system at their most efficient temperatures.
Biomass boilers work well with high output temperatures, and controlled return temps. (say 80/60)
Most heating systems for houses in a retrofit environment should have been designed for condensing boilers, so would be expecting 65 flow /55 return.
You lose more heat through a district main pumping at 80° than at 70° because of the temperature gradient.
Do you therefore mix down at point of use? If not then you'll presumably that means greater cycling of the end user heating system, are the end user control systems updated? - Are the end user heating systems rebalanced and flow / return temperatures of the radiators optimised as part of the installations?
There are loads of extra efficiencies to be had that way. So far all our clients are using significanlty less than predicted when they have comprhensive heating management systems in place.
Biomass boilers work well with high output temperatures, and controlled return temps. (say 80/60)
Most heating systems for houses in a retrofit environment should have been designed for condensing boilers, so would be expecting 65 flow /55 return.
You lose more heat through a district main pumping at 80° than at 70° because of the temperature gradient.
Do you therefore mix down at point of use? If not then you'll presumably that means greater cycling of the end user heating system, are the end user control systems updated? - Are the end user heating systems rebalanced and flow / return temperatures of the radiators optimised as part of the installations?
There are loads of extra efficiencies to be had that way. So far all our clients are using significanlty less than predicted when they have comprhensive heating management systems in place.
Where necessary our temps are reduced at point of use but the reason for the higher temps is that the systems we retrofit into are old stone stately houses with over 100 rooms, old column rads, no temperature control and they are tight with they're money. They are not interested in altering the internal plumbing because "it worked before on the oil boilers" and because we are financing the systems anyway they don't want anything disturbed because other than a cheaper fuel bill, they don't get anything out of it.
Unfortunately there are buildings out there now that have never been heated before as its not required, with a biomass boiler installed burning wood for the fun of it. Like wise although a renewable technology is being used, energy efficiency goes out the window as it has an opposite effect on the repayments. It all makes a mockery out of the whole scheme really.
We went to see a district system in North Devon, no lagging on any of the pipe work, all the pumps and HIUs purposely fitted in outside 'sheds' with no insulation etc
In some respects I'm glad the tariffs have dropped. I'm in it for the long haul and just hope the domestic tariff dropping is enough for the gold rush installers to move on, leaving the rest of the money to fund the customers who make the most of it.
Oddly we are getting more enquiries now for biomass then were we 2 months ago. Fortunately the customers aren't solely interested in it for any return. I just hope it continues like that!
We went to see a district system in North Devon, no lagging on any of the pipe work, all the pumps and HIUs purposely fitted in outside 'sheds' with no insulation etc
In some respects I'm glad the tariffs have dropped. I'm in it for the long haul and just hope the domestic tariff dropping is enough for the gold rush installers to move on, leaving the rest of the money to fund the customers who make the most of it.
Oddly we are getting more enquiries now for biomass then were we 2 months ago. Fortunately the customers aren't solely interested in it for any return. I just hope it continues like that!
Yep, it's one of those anomalies, if you're metered, you'll consume as much as possible. Even in the domestic market, when we install systems to maximise efficiency, if they aren't using up to the EPC figure, then open the windows and wind the heat up else you'll never get the maximum back, and when the payments are greater than the cost of fuel that's what the clients (some of them not all) will do.
I agree, but there is a big difference in thinking between the domestic customers with sub 50kw boilers and the larger commercial customers we have. Wealth breeds wealth, that's all they think about - how much they can get for least outlay. Domestic customers i guess would be much more receptive to having the most efficient controls and systems fitted as the benefit to them is cheaper bills.
We've been to see installations on farms where they have installed copper pipes in the concrete yard to warm the tractor tyres! !!!! And warm air blowers fitted externally .
We've been to see installations on farms where they have installed copper pipes in the concrete yard to warm the tractor tyres! !!!! And warm air blowers fitted externally .
Yep, it's the way of the world. People will find a way to make money out of anything. They should have sewn up the loop holes long ago, somehow. with the amount of money they are giving away they should be doing more inspection to check eligibility. Perhaps they will, I hope they do.
Just for info read here, the press rumors are circulating like wildfire that there will be an announcement at 7am tomorrow morning...
Here we go again- Feed in tariff cuts to come in weeks | Electricians Forums
Got my DECC twitter feed on ...
Here we go again- Feed in tariff cuts to come in weeks | Electricians Forums
Got my DECC twitter feed on ...
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The rumours have been kicking around for solar and on shore for a while, hopefully not a repeat of 2011, do you still do much on the solar side?
RHI is guaranteed until 2016 I believe? Although judging by that meeting, there doesn't seem to be much in the way of security for it beyond then.
The difference with solar/wind and renewable heat is that solar is an emerging market still and a lot of money has gone into the R&D of the technology, which has led to a sharp fall in manufacturing costs. Much of the renewable heat market already existed, we've just been late adopters to it all.
As a small company we're very competitive and can often spec a much better system for less than our competitors. Theres not much room for movement, the capital cost won't come down like it has with wind and solar, maybe it could for non Domestic, the latest cuts will soon see. In fact the RHI may have inflated the installation costs at the beginning?
RHI is guaranteed until 2016 I believe? Although judging by that meeting, there doesn't seem to be much in the way of security for it beyond then.
The difference with solar/wind and renewable heat is that solar is an emerging market still and a lot of money has gone into the R&D of the technology, which has led to a sharp fall in manufacturing costs. Much of the renewable heat market already existed, we've just been late adopters to it all.
As a small company we're very competitive and can often spec a much better system for less than our competitors. Theres not much room for movement, the capital cost won't come down like it has with wind and solar, maybe it could for non Domestic, the latest cuts will soon see. In fact the RHI may have inflated the installation costs at the beginning?
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We put in a couple of pellet boilers to feed a couple of primary schools about 9 years ago. Absolute disaster! Ripped out one after a couple of years and put oil back, other went about three years later, a year after the manufacturers replaced the boiler with another! :banghead:
One site didn't have a buffer tank to start with, soon had the biomass boiler bods changing their minds and saying it needed one putting in as boiler needs to develop a temperature difference from top to bottom to provide a load. Did that but school eventually got sick and tired of the boiler and wanted it out.
Also did a survey at a new PFI school in Bedford four years ago: both Hovel pellet boilers had broke within 6 months to a year of opening, school didn't bother fixing them and happy to run on backup gas boilers as problems with dust from pellet store was causing problems.
One site didn't have a buffer tank to start with, soon had the biomass boiler bods changing their minds and saying it needed one putting in as boiler needs to develop a temperature difference from top to bottom to provide a load. Did that but school eventually got sick and tired of the boiler and wanted it out.
Also did a survey at a new PFI school in Bedford four years ago: both Hovel pellet boilers had broke within 6 months to a year of opening, school didn't bother fixing them and happy to run on backup gas boilers as problems with dust from pellet store was causing problems.
we have taken out quite afew biomass boilers from schools, but when you looked at the system, they were never designed correctly and tbh, the boilers were s~*t, but 10 years ago we didnt know any different. we have replaced some of these boilers with new ones, altered the systems and controls, and had them accredited to Rhi which makes a huge difference to them - and now they are much happier using them.
i just think there wasnt enough technical knowledge in the uk about biomass back then!
i just think there wasnt enough technical knowledge in the uk about biomass back then!
The other issue is staff not wanting to get dirty clearing the ash. One site the caretaker said it wasn't in his job description to clean out the boiler!
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im sure something can be made so it dumps the ash into a galv bucket and the site manager (caretakers new job description 😀 ) empty's/ spreads on garden
It can be, where there's a will there's a way. All of the systems of that size that we install have the option of automatic ash removal into multiple ash storage containers.
However if your agin' it no solution will be acceptable..
Just had a read through of the thread, interesting stuff. Has anyone seen the CIBSE pdf on best practice biomass design considerations,I have attached it but not sure if it will work. If not PM me and I will send it direct.
Somewhere I have another which details a crop of low performing systems, which included oversizing, small buffers, PHE, high temps and no WC in district mains etc etc. basically a lot of the themes discussed here.
We are ETA through and through, and have been through various discussions with tech about how best to ste up. The standard Austrian approach is evidently as per their schematics with 2 port buffers, but they are very wary of promoting this approach, because if the system pump isn't sized correctly their contention was that it can overpower or conflict with the return riser and draw too much heat away from the boiler.
The benefit is that the boiler and buffer can as as has been discussed work together to cover a larger load, destratify slower or satisfy the heat demand as the boiler comes to temp but with lower destrat levels.
We have done it once on a log gas boiler and it does work well, 30m of pre-insulated in a pipeline set up, DHW priority, WC for heating so it ramps to full output for the cyl and then drops back to the curve once satisfied.
Not had the balls to do it again tho or on a bigger system, always default to the 4 port!
Somewhere I have another which details a crop of low performing systems, which included oversizing, small buffers, PHE, high temps and no WC in district mains etc etc. basically a lot of the themes discussed here.
We are ETA through and through, and have been through various discussions with tech about how best to ste up. The standard Austrian approach is evidently as per their schematics with 2 port buffers, but they are very wary of promoting this approach, because if the system pump isn't sized correctly their contention was that it can overpower or conflict with the return riser and draw too much heat away from the boiler.
The benefit is that the boiler and buffer can as as has been discussed work together to cover a larger load, destratify slower or satisfy the heat demand as the boiler comes to temp but with lower destrat levels.
We have done it once on a log gas boiler and it does work well, 30m of pre-insulated in a pipeline set up, DHW priority, WC for heating so it ramps to full output for the cyl and then drops back to the curve once satisfied.
Not had the balls to do it again tho or on a bigger system, always default to the 4 port!
Just finished a Froling log boiler as per the 2 pipe method, weather compensation and DHW. As above, works well, heat even when the buffers not loaded.
Strangely, Hargassner suggest a 4 pipe method for pellet, 2 pipe for log. Possibly due to buffer volumes.
Strangely, Hargassner suggest a 4 pipe method for pellet, 2 pipe for log. Possibly due to buffer volumes.
N
Norcs
A buffer, volumiser, accumulator, thermal store etc should only be fitted as a last resort as they only add to the heat load, add a lot of cost to the install and lose heat for a past time.
If the boiler modulates or good control can be added to avoid cycling then that's the way to go.
If the boiler modulates or good control can be added to avoid cycling then that's the way to go.
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