Prioritise Radiators over hot water?

coffeyt

This may not be right or possible but I'm wondering there a way to prioritise heat going from a back boiler to the radiators rather than hot water?

I have a stove with back boiler and when it's going i have hot water galore but the radiators only get hot for a while and then lose heat. The pump is working fine and all the radiators do get hot but don't stay hot for long even with a good fire going. They are heating up and losing heat on a cycle, I may be wrong but I'm assuming the hot water is being prioritised.

I have no need for all the hot water in the tank as removed my bath and replaced with electric shower and would prefer If the radiators were getting hotter and staying hot. Is there a way to do this?

or maybe I'm just not using the stove the correct way, I'm at a loss really as there is loads of hot water and stove is roasting but I can't keep constant heat in the rads.

John.G

Is there a pipestat on the boiler outlet set maybe to 55C which starts up the circ pump to the rads and shuts it down at ~ 45C,

coffeyt

Yes there is, it is currently set at 50, I'm not sure if that is the right setting or not!

John.G

How far away from the boiler is it to where attached to the flow pipe? and does the pump come on (is it running), you can test it by turning the stat stting down, you will hear a click and then the pump hould start, if you tun it back up by about 6 to 10 deg you should hear another click and the pump should stop.

coffeyt

The tank is about 8ft away from stove and I have checked the pump by turning the stat up and down and it turns on and off no problem..I can hear the pump engaging and it lights up. It doesn't seem to stay on for long however. All the radiators are heating up initially but they really seem to just lose heat and then reheat again. Should the pump be running constantly or should it be cutting on and off (this is what it seems to be doing)

Wearb

Sounds like too much expected of not a big enough fire.

John.G

Yes, but also, and very important, if the pump is on too high a setting then it will cooll down the water too quickly and while the same amount of available heat is transferred to the rads in short bursts, its far better to slow the pump down which will keep a more constant heat to the rads which is better.

So can you post a photo of the pump and its name/model and settings, if you don,t know the setting post a photo with it running and I can suggest a more appropriate setting, hopefully.

The cylinder is 8 feet away from the stove but how far away is the pipestat from the stove??.

coffeyt

Thanks for the help, that makes sense as the pump is currently set at 3 which I assume is the highest setting. I will attach a picture, hopefully it uploads ok! I think the make model is as follows: WILO Yonos PICO 25/1-6-130-(ROW)

I hope that's correct as I was reading it upside down.

The pipestat is about a foot from cylinder so its about 7ft from stove.

16659882953617336133743075142727.jpg

John.G

OK, I have one of those, a lovely pump, mine has slightly different controls but doesnt matter.

When it next comes on note the power W in watt, then just turn the switch a tiny bit towards setting ii, the display will flash for a few seconds and display the pump head setting in M (meters) and then revert to displaying the head M, note this. I cant actually see if there is a mark on the switch, post back both readings. OR when the pump is running turn the swoitch until its pointing towards the picture with the pump curve with a sloping line, that is proportional pressure (PP) control keep adjusting it until its flashing 4M and then read off the power W and post back.

OR

EVEN EASIER Even if the boiler isnt on just turn the pipestat down to start the pump and its easier to set it up then.

Picture of my pump, below.

Wilo Yonos Pico Mine.jpg

John.G

OK, thats not quite the same (modes) as mine.

So, as above turn the stat down to start/keep the pump running, read off the power W (watts) very slightly move the switch until the head (M) starts flashing and note it. Keep turning the switch slowly until the head reads 2.5M, then read off and note the power W (watts), do not use the PP settings on the other side. reset your pipestat to 50C. Post back

coffeyt

Ok, thanks for all the help so far and I hope I did this right.

Both numbers appear to be very similar, I turned down the pipestat to get pump on and it came up as 4W and 4.1M. I turned the dial slowly until it was 2.5M which read as 2.5W also so I'm not sure if I did this right. The dial is now set midway between 1st and 2nd setting.

coffeyt

Right since I've done as advised and left the setting on the pump at lower setting, the pump kicked in a few mins later and has been on constantly for the last hour. All the radiators are hot top to bottom and seem to be getting a constant level of heat into them.

fingers crossed it's looking good, thank you!!

John.G

Those numbers make no sense to me , a 4.1M head should result in a power demand of 16/25W or greater, will look at pump curves soon, which one of modes was lit up, if any, the one with the horizontal line or the one with the sloping line??

coffeyt

Ahh I was wondering about the numbers alright the way my one lights up is beside the screen you have a M and a W underneath, it lights up with a number and the letter so for example it flashed and lit up as 4.1 with the M also lighting up, then the M turned off and the number changed to 4 so I assumed that was the wattage (even though I was thinking it didn't make sense) As I turned the dial down the number reduced and the M lit up again and remained lit until I stopped at 2.5. Maybe I didn't wait long enough for the number to change? I will have a look again but the W itself did not seem to light up at all.

coffeyt

Actually looking at the screen now i think it's actually reading 25, the M is not light up and I think the decimal point is gone, when I turn the dial and it flashed the M lights up and the decimal point is more obvious.

John.G

Just to be clear, when you turn the switch just enough, the requested head will flash for approx 3 to 5 secs the power will then be displayed permanently, so set the head to 2.5 and then post back the power W.

is any one of the horizontal or sloping line symbols illuminated??

Also W is M when upside down.

coffeyt

Yes that's perfect, I set it to 2.5M, it proceeded to flash then it changed to 24.

nothing else lights up on mine?

it's showing consistently now at 24.

John.G

You must have a very unrestrictive system as that pump is circulating 25LPM at a 2.5M head, it may be circulating through the HW cylinder as well and not just the rads but that's not a huge problem once the cylinder is up to temperature, keep a eye on the rads flow/return temps, the pump should now only be pumping ~ 64% of previously so sould increase the time between pump start/stop, depending on your findings you can always reduce the pump head incrementally in 0.1M steps, one of the big advantages of the Wilo. Give us a shout now and then.

coffeyt

Thanks a million for all your help, it's already improved massively compared to the last week where the heat in rads were constantly up and down, I'm now getting more consistent heat into the radiators which is what I was after.

I'll play around a bit more with the pump as per instructions and see how it goes.

10-10-20

I must say, pretty dedicated support there @John.G! You certainly know your stuff.