As in I, from perusing the Grunflos webpage, figger that these pumps are controlled by pressure rather than temperature.Yes?
Reason I am asking is that we have a 40kw wood burner linked through a Laddomat to a 2200 litre buffer tank.
I can get the tank up to say 90 deg at the top & 80 at the bottom.
BUT when I start drawing off heat during the spring or autumn when my heat demands are marginal, I lose stratification,............ in the dead of winter no problems since I am lighting every day anyway.
So I reckon that I need a TEMPERATURE controlled circulating pump.
btw I pump straight out at max temp to hot cyl (in the house,) rads and also underfloor with its own self contained blending setup.
So I may need fit a blending valve as well? yes
though I am pleased with the higher temps at the rads,and indeed for domestic hot water, I simply run the pump for a shorter time.
cheers
M

I'm using a Wilo-Smart self modulating pump on my rad flow circuit set to the lowest setting and all rads have TRVs except one. I left one rad without so the circuit would not 'close' and damage the smart pump.

I'm now wondering if the smart pump would stop pumping completely if all TRVs closed down and I shut off the LSVs on both sides of the other rad?

All rads get nice and hot with the LSVs turned right down to balance the temp accross them. The downside to this is you can hear the water flowing through under pressure.

Is there anything you can do to eliminate this noise other than open up the LSVs?

Erm?
I bin pondering that Mike.
I only need one thermostatically controlled three port on the ret pipe, between the buffer tank & the circulating pump, with the thermostat att to the ret pipe & set at say 40/45 deg, if the return flow is hotter than the limit, it diverts the hot water back into the "flow" pipe via a plain "T" .ie. rather than into the buffer tank.
If the ret water is cooler than the preset limit of 40/45 if dumps it straight back into the buffer tank, drawing the hotter water off the top of the buffer tank.
I figgered this because no matter if I fit a blending valve on the hot output from the buffer tank, it will still dump a %age of warmer water into the bottom of the tank
I can ( and do already ) run the underfloor to dump the low grade /temp heat, I can pull the entire buffer tank down to 25/30 deg this way, whilst usefully heating the house.
NOW HOW this will interface with the workings of the laddomat?
cos at present when my buffer tank is cold, and I light the boiler, the tank STAYS cold, bottom to top whilst the hot water is sent straight to the radiators, but through the buffer tank? Cos that is how it is plumbed.
Quibber & titch & numble

Hello, everybody,
Our home was originally plumbed with an indoor Firebird Oil Fired Boiler, situated in a cupboard under our kitchen counter-top. This supplied the heat for our central heating, which is split up into 4 zones, with TRVs on all of our 31 radiators. It also heated our Domestic Hot Water via a Heat Exchanger and an 80 gallon Storage Tank (Insulated Copper Cylinder).
Now, we have installed a new Multi-Fuel Boiler in our shed along with a 2000 litre Buffer Tank, which is tee-d into the old system. (Please see the attached drawing). This new system is wonderful, we have heat all over the house with loads and loads of hot water. Our home is a Bed and Breakfast and needs a constant supply of hot water and heat most of the time.
Our old oil fired system would cost a bomb to come near the comfort the new system offers. It’s amazing! It is set up in a way that allows for the oil boiler to come on should the temperature at the top of the Buffer Tank fall below 45 degrees C. (this can be adjusted to suit our needs, but we have it set to 45 degrees C.)
Should the temperature at the top of the Buffer Tank fall below 45 degrees C. Thermostat T4, at the top of the Buffer Tank (on the drawing), opens MV1, closes MV2 and switches on the Oil Boiler (OB), thus isolating the Multi-Fuel Boiler (MFB) and Buffer Tank (BT).
The cartridge in the Laddomat (L) is 63 degrees C. and the Multi-Fuel Boiler is set at 65 degrees. With these settings the Temperature Gauge (TG1) at the top of the Buffer Tank normally reads around 70 degrees C., with the bottom Temperature Gauge (TG2) normally reading around 60 degrees C.
We have one problem, though, when we have no heating on (during warm weather) the heat in the Buffer Tank can go up to 80 degrees C. at the top and up to 70 degrees C. at the bottom. This can cause the Domestic Hot Water to become very hot and, at times, cause the water in the Storage Tank (ST) to over-heat and push hot water up the Expansion Pipe (DHW/EP). At this stage the water in the taps becomes dangerously hot and is a worry. We certainly don’t want anyone getting scalded.
Thermostat T1 for the Heat Exchanger is set to 60 degrees C. and Thermostat T2 is set at 55 degrees. Thermostat T1 switches on the Heat Exchanger Circulating Pump (P1) when the temperature reaches 60 degrees in the flow pipe from the boiler. Thermostat T2 switches off P1 when the temperature at the bottom of the Storage Tank (ST) reaches 55 degrees C.
We are also afraid of children touching the radiators when they come on with 80 degree water in them. There’s something telling me that we need to fit a mixing (blending) valve between the flow and return at the house side of the Buffer Tank. Would I be correct in saying this?
I would really appreciate any help or advice on this.
Thanks.
Tom.