Heat Transfer System - Limited impact

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Nomad1963

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#304560 15-May-2023 11:29

Hi all,

I have a 4 roomed Weiss heat transfer system installed in my house but it does not really warm up the rooms, although it does take the chill off; the ducting is 150 mm

I know that the system is not an ideal system for the house as it is designed for a 2.4 metres ceiling height and my rooms are 3 metres

The air intake grill is located 3 metres from the inbuilt wood fire

Questions.

Is the intake grill too far away from the fire?

Would changing the intake grill to a 200 mm - now 150 mm ( using a 200 mm - 150 mm reducer ) increase the amount of warm air being transferred?

I am not sure if this would work or if I need to buy a stronger motor or replace all the 150 mm ducting to 200 mm

I am using a ceiling fan in one room which seems to help.

Any idea or advice would be greatly appreciated.

Thanks

Nomad

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#3076297 15-May-2023 11:44

Is the grill direct above the fire? I'd suggest you measure the temperatures above the fire and at the intake to see if moving it is worthwhile. An IR thermometer can be useful for this. I suspect above the fire would make a significant difference.

Another thing to look at is the diffuser in the bedrooms. The most commonly used diffusers push the air sideways across the ceiling, whereas it really needs to push it down towards the floor. This made a big difference with a ducted heat pump, it would with a heat transfer system as well. Have a look at diffuser suggestions in this thread.

Regarding ducting / motor, I'd look at the specifications for the ducting and the motor and see if I could work out where the bottleneck is. If you replace ducting / fan you're pretty much replacing the whole system. I'd look at this after the first two suggestions above.

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#3076303 15-May-2023 11:58

Our intake vent is probably about 2m from the fireplace, but takes a little while to distribute the warm air as the lounge has to warm up first.

Not sure what size our intake is. All the exit vents are in standard bedrooms, and just take the chill off rather than heating the room.

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#3076307 15-May-2023 12:07

Is the roof space Ducting "Insulated" this will 100% make a major difference. (I have seen some installs go 'cheap' and use non-insulated ducting, which is a recipie for fail.
(even insulated ducting has significant heat loss - as Insulated ducting has limited thermal capacity simply due to physics.)

Changing the size of the Intake will make no different, - as it is still limited by the reducer.
Changing the 'power' of the existing in-line fan would make a difference, - and so would changing the size of the Ducting.

As people has said - the 'style' of the outlets may make quite a difference - as you may find all your hot air is 'transferring' and it is simply sitting above Head height, with your heigher ceilings (as indicated by your room, where you see benefit from the Fan.

snowfly

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#3076373 15-May-2023 13:25

We have a 3 bedroom system from "Heat Trans", expanded to a 4th room, which is a SimX system, and works great, but as mentioned by others, there are a few key points to help improve the efficiency of the heat transfer system:

Our inlet is approx 2.5m from the fireplace, was advised not to install it directly above fire
200mm inlet and pipe to fan
Powerful 200mm fan
200mm to a 3 way spliiter > 3 x 150mm
One of the 150mm ducts then splits again, 2 x 150mm, for 4th bedroom
We upgraded to R1.0 rated ducts with 70mm thick insulation (standard was R0.6 ducts)
This helped the most, plus we had some spare ceiling insulation segments, so placed these over ducts & junctions to help with less heat loss.

Suggest checking your duct size from inlet to fan, then fan to rooms, perhaps upgrade fan, and upgrade to better insulated ducts.

timmmay

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#3076388 15-May-2023 14:07

snowfly:

We upgraded to R1.0 rated ducts with 70mm thick insulation (standard was R0.6 ducts)

My R1.0 200mm ducting doesn't have insulation anywhere near 70mm thick. It's more like 10 - 20mm thick. 70mm thick would be closer to R3 or R4 I guess.

I had some R0.6 ducting removed, the insulation was really quite thin.

snowfly

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#3076392 15-May-2023 14:12

timmmay:

snowfly:

We upgraded to R1.0 rated ducts with 70mm thick insulation (standard was R0.6 ducts)

My R1.0 200mm ducting doesn't have insulation anywhere near 70mm thick. It's more like 10 - 20mm thick. 70mm thick would be closer to R3 or R4 I guess.

I had some R0.6 ducting removed, the insulation was really quite thin.

The 70mm thick thermally insulated ducting I got was from SimX, specs here do mention R1.0:

https://simx.co.nz/images/uploads/resources/02_Grilles_Diffusers_and_Ducting_Section_2022_-_Flexible_Ducting_-_Unilok_FR1.pdf

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#3076411 15-May-2023 14:34

snowfly:

The 70mm thick thermally insulated ducting I got was from SimX, specs here do mention R1.0:

https://simx.co.nz/images/uploads/resources/02_Grilles_Diffusers_and_Ducting_Section_2022_-_Flexible_Ducting_-_Unilok_FR1.pdf

Interesting. I don't know what brand I have, whatever the installers used.

tweake

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#3076427 15-May-2023 16:48

Nomad1963:

Hi all,

I have a 4 roomed Weiss heat transfer system installed in my house but it does not really warm up the rooms, although it does take the chill off; the ducting is 150 mm

I know that the system is not an ideal system for the house as it is designed for a 2.4 metres ceiling height and my rooms are 3 metres

The air intake grill is located 3 metres from the inbuilt wood fire

Questions.

Is the intake grill too far away from the fire?

Would changing the intake grill to a 200 mm - now 150 mm ( using a 200 mm - 150 mm reducer ) increase the amount of warm air being transferred?

I am not sure if this would work or if I need to buy a stronger motor or replace all the 150 mm ducting to 200 mm

I am using a ceiling fan in one room which seems to help.

Any idea or advice would be greatly appreciated.

edit: what size rooms do you have?

whats the temp set on the controller?

where is the controller mounted?

is the lounge getting above the temp set on the controller? they only move excess heat, so if there is no/little excess heat then its going to move none/little.

the motors will blow a huge amount of airflow, the are generally used at slow speed to keep noise down.

duct size is more about length of ducts. long ducts, especially the main truck may need to be larger.

a BIG thing often overlooked is the return path. it must have good flow back to the lounge (or wherever the fireplace is).

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#3076428 15-May-2023 16:52

Heat transfer systems often have pathetic little 150mm fans delivering perhaps 100l/s or less. It's very much dependant on the fan size.

Jase2985

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#3076448 15-May-2023 17:36

reverse the fan, have the cold air being exhausted above the fire, it will heat quickly and you likely wont notice it, and as the cooler air is sucked out the rooms it should suck the warmer air from near the fire and heat the rest of the house.

But 150mm is small for a 4 duct system.

andrew75

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#3076480 15-May-2023 20:50

Use a thermometer (I use a kitchen thermometer) and measure the temp difference between the intake and outlet.

If large, further insulating the ducting may help.

If not large (and I suspect this is the issue) it is probably just not enough air flow to make a difference. I've got heavily insulated 200mm ducting throughout and a 200mm fan, and the system makes a big difference - the rooms don't' get 'toasty' but a comfortable temp, and it avoids the fire room roasting.

k1w1k1d

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#3076487 15-May-2023 21:52

I installed a 3 room 150mm system and it was next to useless. Too much restriction in the ducting resulting in very low air flow to the bedrooms. Should have used 200mm.

I have another 150mm fan that I intend to put on the front of the 3-way splitter to boost the air flow. Not worried about noise as we turn it off when going to bed.

Should actually do that this weekend now that winter has arrived.

timmmay

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#3076537 15-May-2023 22:06

Jase2985:
reverse the fan, have the cold air being exhausted above the fire, it will heat quickly and you likely wont notice it, and as the cooler air is sucked out the rooms it should suck the warmer air from near the fire and heat the rest of the house.

But 150mm is small for a 4 duct system.

I'm not sure that will work. Most houses aren't sealed, it could just suck more cold air in from outside. For it to work the warmer air up high would need to be pushed into the bedrooms at floor level.

I suspect pushing warm air in through decent diffusers is probably more likely to work.

MadEngineer

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#3076553 16-May-2023 02:05

When did you have that installed?

https://www.weiss.co.nz/ht_recall_2014

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jm3

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#3076667 16-May-2023 10:16

We have a 3 room simx transfer system with the 0.6R insulated ducting. It is hard to heat up the rooms without making the lounge sweltering but it does help take the chill off as the night cools. Here are some stats from the other night when we had the fire and transfer system running from around 5pm until 8:30pm. We usually turn the transfer off when kids are sleeping.

Does anyone else have some stats for comparison?

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