Adding additional radiators to existing heat sink

[Saval]

Hi, first time on here to ask question, but have read forum on quite a few occasions so thought I might get a good answer to my question

Is live in a relatively new house in remote highlands, with underfloor heating charge by a Wamsler wood burning kitchen range. However this doesn't work properly as was poorly designed and installed to deep within the slab. It takes a huge amount of continuous effort and wood to keep the stove going to supply enough heat to work the underfloor system and even then only a little heat is actually felt within the floor.

We currently run two radiators off the stove as heat sinks, these are controlled by a thermostat but I have manually locked it open so they are on all the time.

So my question....can I add additional radiators to one of these heat sinks, this one is in a downstairs bathroom. Is it possible to add at least one to the next room and two upstairs immediately above the existing one. The heat sink is a tall chrome wall towel radiator and is supply by flow and return pipes from above out of the ceiling. My intention would be to run pipework along the top of the room and through the wall to the next room and fit another tall panel radiator. The two above tee off on a separate lines, in ceiling spaceand put through floor to the radiators.

Any helpful advise would be great

 

[JohnD]

how much wood does this stove burn per day, and what is its output in kW? Wood contains far less heat than solid fuel, per bucketful, so I am not surprised you have to keep refuelling it. Will your stove burn solid fuel?

What is the calculated kW rating of your UFH?

What is the size of the room with the UFH, and what is its heat loss?

What size are these radiators you mention, and what is the temperature of their flow and return?

 

[Saval]

Hi, thanks for the quick response, yes the stove will burn coal, but we dont, partly out of principle and because we have a abundant supply of wood here.

I've considered installing a separate woodwhisper/pellet boiler or large log boiler. But I like too use the existing system more efficiently for now.

The wamsler puts out 25kw in total, with 18kw going into the water, which is 61,000btu.
We tend to the stove between 4pm and 9am everyday which usually supplies enough hot for each following day. We burn roughly a barrow load of wood and day. Which is usually softwood pine and larch. If we need it on longer periods we can burn oak. We don't normally run the underfloor heating as it takes so most effort and drains the heat.
The stoves charges a 1000l thermal store, with a flat plate heat exchanger for hot tap water.
Without running the ufh I'd think there more than enough heat capacity in the stove to run additional radiators. I just unsure about the set up, as the the heat sinks come off the back of the stove pipework, off of the stove to tank line which is 28mm to 15mm to radiators. Water is usually around 65DegC and the two existing radiators are scalding hot.

I haven't quite decided on sizes of new radiators but would probably be double type 1.8m x 0.6m in two upstairs rooms and probably the same in the groundfloor room but vertical instead.

I'm just wondering about whether existing pipe sizes would be ok and about air locks or whether it would need to be pumped

 

[Norcon]

Between the wamsler and the 1000l store you need a laddomat type valve fitted.

And the pump triggered by a flue stat on the wamsler.

Are any devices like this fitted?

Without this cold water will constantly flood the boiler lowering the efficiency and if the current pump is controlled by a water stat then when the fire dies down the pump will continue running cycling all the contents of the store through the boiler and losing the heat up the chimney.

Underfloor heating from cold in a screed will absorb huge amounts of energy.
And if that's combined with the store without the correct control strategy then the wamsler will struggle even if the sizings look appropriate.

 

[Saval]

Ok, there isn't a laddomat valve or stat on flue.

There are 3 stats fitted to pipework. One is fitted to the hot feed from stove to store(set at 50deg) which controls a pump to mix that hot water with cold water being fed back to the stove, so probably trying to do the same as the laddomat. The second is fitted to the cold feed at the stove and regulates the valve to the heat sinks. The third is on the cold feed too but at the store and controls the ufh pump which pushes hot water to the two ufh manifolds.
These stats are probably set wrongly, and I might reset to 70deg and put on stove to see what happens

If be worried that that stores setup is probably wrong.
The kit was supplied by invisible heating systems and when our plumber had finished we were left with a box of bits and a large expansion tank?
It's a vented system so doesn't need the tank...right???