update for r2d2,water sys and jimbo

I wouldn't be happy with the bill when you consider he is on gas and not oil, on the other hand the system seems to be badly designed and installed with an obvious need for better controls.

i agree with your comments on the boiler, sounds a right load of rubbish. Mind you it's is a Potty.

 

The 50mins to raise the temperature through 60c and
the 2m³ (21Kw) of gas is actual give or take a few
degs C Water Systems.

Water Systems;

In hot water priority, does the boiler remain on high
flame untill the store is satisfied or does it
modulate down and trickle charge say the last
10-20c.<u></u>

I'm not sure how the Powermax operates on re-heating DHW. It may modulate the burner down towards the end of the re-heat. However, they design for a rapid reheat to get to CH mode ASAP. They design the heating coil to match the burner. It needs some observations when reheating. A call to Potts tech dept may solve it. However how the control systems work appears to be totally beyond the people on the phones in any company. I started to tell one guy on I think the Glow Worm tech line, how their control system worked. Words like "load compensation" goes over their heads. They tend to know it modulates, but don't know how and why.

The Powermax is a decent boiler - surprisingly for a Pott, and WatchDog on TV blowing them up over the Suprima is way before time. It should work OK on UFH and rads. It just needs careful design of system and controls that's all.

 

Water Systems.
How would that boiler cope with direct boiler compensation to trim down the flow temperature say to suit the radiator circuit.

Would the modulation operation be curtailed as the boiler is interlocked at a lower flow temperature.

 

Water Systems.
How would that boiler cope with direct boiler
compensation to trim down the flow temperature say
to suit the radiator circuit.

Would the modulation operation be curtailed as the
boiler is interlocked at a lower flow temperature.

The flow temperature does lower (modulation), however not not via a weather compensator.

If say a pipe stat is on the return (the return temp is more stable so no excessive boiler cyling. The situation is the same as having a room stat. The flow temp modulates down as the return temp rises and then the on-off stat cuts in to cut out the pump and boiler.

I'm not sure if Potterton have any room stats that mesh into the contol system that will further modulate the burner with room temperature influence until the room temp is over setpoint and then boiler/pump is off. Some makes do have these: Viessmann, Ferroli, etc. Some have weather compensators that mesh into the control system too, add outside weather influence on the modulation. Although one of these stats is not much use in this situation.

 

The flow temperature does lower (modulation),

Yes ,but I was of the impression that this is only to maintain the flow temperature at 80C.
Their are no simple manual controls on this boiler to prevent the boiler reaching 80C.

Lets say we wanted to set the boiler at a maximum flow temperature of 70C, then this seems not to be possible with this boiler.

 

it would be simple to control the heating via a small header and either zone valves or diverter valves similar to the pic I posted.

You could control the delivery temp to each zone via room stats etc, and let the boiler top up the header.

The underfloor circuit seems to be where the biggest problem is, I would control that down to 50-55c up to the manifold blender, and 35-40c in the loops, (assuming enough pipework has been installed). I would also do away with the manifold stats ( they ain't needed ) and instead control the primary circuit to each manifold via a programmable room stat.

 

I would also do away with the manifold stats ( they ain't needed

If you mean the electrical thermostats controlling individual rooms then I am in agreement with you Doitall however you could fit Danfoss FHV-A,s in certain rooms if you wanted to give localised control.Similar to TRV,s on raditors.
The saving not fitting on all the other <u>expensive</u> electrical components associated with manifold actuater control would easily pay for this-

http://europe.hbc.honeywell.com/products/pdf/mu1h0207-ge51r0902.pdf

Page 41 shows a layout which would be suitable for the OP's, system.

 

A good plan r2d2, but a tad OTT, a small header with a zone valve for each circuit, and a room stat to open and shut it, is all it needs.

 

but a tad OTT

Ask this guy if its a tad OTT.

http://www.leemick.co.uk/

Another very good controller is Honeywell,s Aquatrol 2000 which will whack ££££ of heating bills.
Not for your average semi though.
Where you make the saving to make a controller like this affordable in the larger residence is to forget about individual room control via electrics which pushes the UF cost up considerably.
The Aquatrol is slightly less flexible as regards the number of mixed heating circuits it can control but it more than makes up for this with the array of boiler control parameters that can be set up upon commissioning.

 

One of the good guys

Not saying your's isn't a better system because it is on a larger scale.

Two problems that come to mind.

A 5 bed house is not very big (larger residence). But more to the point, you cannot control the boiler it seems, only the water that comes out of it, and at 80c its way too high, therefore the next best bet is to reduce the quantity of water at 80c down to a minimum, that way the boiler will modulate and shutdown much quicker, in the meantime you can draw off water from the header at any temperature you like.

 

Hi

Sorry but 9 pages!!!!!!
I got the best bits.

Re boiler flow temperature. The controller we use can either control boiler flow or return. It calculates the temperature of the flow / return required and switches the boiler accordingly. If a flow of 50 degrees is required the controller will switch the boiler to maintain 50 degrees. The differential on the boiler is also controlled by the controller but it is changed depending on speed of temperature response (If the return heats up quickly the differential is wider) and if the return heats slowly (High demand) the boiler differential is smaller.

We have found that we can maintain a required and even supply water temperature (unless the boiler or pump is way over sized)We have also found that using this type of control will keep a condensing boiler in condensing mode for longer

 

Just to add a little more...
We always tell our clients that their is two ways to control UFH.
1. Cost effective (Time clock controlled night setback, Variable water temp control)
2. comfort (24hour run, full compensation over boiler (Rads or low mass UFH) and a 2nd compensator for UFH (High mass)with night setback

We only use electronic room control (Most mechanical stats have 3-6 degree differential) and now days the stats(Sensors) that we use are proportional.

BUT.... Most sites that have this type of control are large residential (1.5 million plus (but in our area thats 4 bed detached land))and commercial (Schools nursing homes and central boiler houses for flats)

The main issue that we get from our clients is they think they want energy efficient control but what they mean is

Heat where and when wanted (Now). Hot water that never goes away and at the tap in 3 seconds. (Gas bill ?? so long as its below the cost of the x5 on the drive its ok)

And if they dont get the heat or water as above they call their solicitor not their plumber

 

My last bill was £25 & was a metre reading I just reviewed my bill for the quieter on line & now they are saying £145 I have not used extra gas & when I submitted my metre reading it says it's to low a metre reading please try again. You don&#146;t get a £5 early payment discount now but if you&#146;re late paying they charge £5

 

leemick you sound very knowledgeable

Yes indeeed he is and a specialist UF heating installer.
I would suggest contacting his company direct at the link I gave and he may be able to help you.

List prices for Kanmor controllers range between £400 and £1000 pounds plus installation costs.
Their not something you can diy as a sound knowledge of heating control systems is required.

 

Hey r2d2 i will have to start paying for recomendations like that. Thanks.

The kanmor controllers will connect to any boiler, they just wire to a switch live to enable the boiler. The brains in the kanmor (I still use Tekmar it sounds better)will either send the start signal or not send the signal.

The controllers come in many formats boiler compensation, 4 port mixing valve compensation, Variable speed injection compensation, Boiler and Variable speed injection compensation,Boiler and 4 port mixing valve compensation, 2 boiler sequence with compensation and many others.

Each system we look at seems to require a different controller.
Its allways fun to retrofit into an existing system but a sound knowledge of the system is required.

As far as the potterton is concerned straight forward boiler compensation set at a max of 50 degrees and compensating down to 20 at 18 O/S Air temp. The boiler will switch internally for HW to maintain its stored water system and will give HW priority via its internal 3 port valve (Im not a boiler guy but i think it works like that)

When the flow aproches compensated setpoint the compensator will switch the boiler off but keep a pump running to use the heat when the flow drops enough the control will enable it again. The only draw back is if the boiler is oversized it will cycle.