Heat Loss Calculations Complete - What Next?

[Triassic]

Having downloaded Jeremy's Heat Loss Spreadsheet and populated it using figures supplied by the Architect, it tells me I have a Total Heat Loss of 5766 watts. (The higher than expected result apears to be driven by the number of windows we have).

 

The question is - What Next?

 

I assume I'll need to have some heat input to balance the Total Heat Loss of 5766 watts? I had in mind to install underfloor heating in the groundfloor slab and heat spreader plates and pipework in the kitchen / family room. (the house is basically an upside-down house, with two bedrooms and a lounge  downstair and a Kitchen/family room and dining room above.

[PeterW]

Yep

 

 so take your ground floor area, and heated first floor area and divide the loss by the area in square metres. Gives you the w/m2 you need to put in. 

 

From that you can calculate pipe centres and heat input. LoopCAD is good for this too if you can translate UValues to R Values as it’s a US product. 

 

Dont forget heat from towel rails etc all goes into the mix 

[Alexphd1]

Tbh I never considered what to do next after working out heat loss.... I just worked out v rough heat loss then added on a few kw for hot water allowance for looking for a inverter heat pump. We installed ufh at 200mm centres with the long term plan of trial and error with lowering the ufh temp as low as possible and still heat/maintain room temps. 

[ProDave]

You can now also play "what if" and see the effect of better U values for windows, doors, walls floor, roof etc and see where it might pay to make improvements.

[Triassic]

3 hours ago, PeterW said:

Yep

 

 so take your ground floor area, and heated first floor area and divide the loss by the area in square metres. Gives you the w/m2 you need to put in. 

 

From that you can calculate pipe centres and heat input. LoopCAD is good for this too if you can translate UValues to R Values as it’s a US product. 

 

Dont forget heat from towel rails etc all goes into the mix 

I've now used Loopcad to produce drawings etc for the UFH layout. It suggests 4 zones on the ground floor and 5 zones on the first floor.

 

Regarding manifolds, would it be best to have two manifolds, one for the GF and one for the 1st floor? or just one 9 zone manifold?

 

1 hour ago, Alexphd1 said:

Tbh I never considered what to do next after working out heat loss.... I just worked out v rough heat loss then added on a few kw for hot water allowance for looking for a inverter heat pump. We installed ufh at 200mm centres with the long term plan of trial and error with lowering the ufh temp as low as possible and still heat/maintain room temps. 

How many is a few Kw for hot water?

[Alexphd1]

One manifold could be a nice solution, never seen it done before. Would be better for manifold upstairs for air. One less pump etc to buy run etc.

 

We allowed 3kw for dhw but their is no scientific reason for this, prob better to wait for someone with more experience on this.

[le-cerveau]

3 minutes ago, Triassic said:

Regarding manifolds, would it be best to have two manifolds, one for the GF and one for the 1st floor? or just one 9 zone manifold?

 Your probably best with 2 manifolds, as you will add a good length onto each run that is above/below the manifold and have a bugger of a time balancing for the different flows taking into account the flows up/down hill.

Are you running the whole house at one temp (PH style) of zoning the loops with thermostats this will affect your final decision also?

Are you including towel rails (I didn't and should have) you can run them of a separate manifold at a different temperature (control strategy).

13 minutes ago, Triassic said:

How many is a few Kw for hot water?

Unless it is a tiny house this is easily manageable with low temp UFH, we are about 4kW in 400m² PHPP calculation and 5 human bodies and white goods are keeping the house warm.

[Triassic]

@le-cerveau is was thinking two manifold might be better, as you suggest it might help with balancing the flows to upstairs and downstairs.

I was thinking about running it all at one temperature. In my last house, each zone had a thermostat and an actuator. Would these be required in a PH style set up? If not, what sort of controls would be necessary?

 

Assuming 4Kw for hot water and the 5 Kw for UF heating,  I have a total load of around 10Kw, so do I need a 9 Kw ASHP?

Edited April 17, 2018 by Triassic

[le-cerveau]

I have two manifolds, each with their own pump, fed by one TMV (because I can also cool the system so that bypasses the TMV in cooling mode)  I have one thermostat (2 actually heating and cooling) that operates a 3-port valve to select water from the TMV (provide heat at 26^oC, I may be able to dial this down) or towards the cooling circuit (constant circulation).  This does not provide cooling unless the cooling thermostat operates and then the ASHP injects cool water into the circuit.

 

I have a 9kW ASHP that provides low grade heat to 2 x PCM34 Sunamp batteries (buffer tanks with DHW pre-heat) and a boiler for DHW top up (PCM58 cells) these may be replaced by traditional SunAmps (Electric re-heat) (in the future) as I have 10kW of PV!

[Alexphd1]

I don't see any problems with balancing system with manifold upstairs, only major downside to one manifold is being restricted to one temp for both floors. You may/probably need two different temps in spreader plates and screed. As for heating controls doesn't make any difference one thermostat controlling everything or 9 thermostats controlling 9 zones. Not 100% on cooling side haven't considered it. 

 

One word of caution on bigger spaces you may need 2 or 3 loops per room ie bigger manifolds.

[PeterW]

I would say a single manifold upstairs is fine although you may want to run the rooms slightly cooler so you’re talking about using zone thermostats anyway. 

 

Its  pretty easy to run 2 zones with a common link to the pump, and also trigger a boiler or ASHP if your are not using a buffer. 

 

Both me and @Nickfromwales reckon those auto balancing manifold actuators will pay for themselves over and over - I would also go for a 10 port manifold and chuck the AAV on the top rail so is the highest point as we found that air collects in the top rails as the ones on the end aren’t high enough up. 

[Triassic]

3 minutes ago, PeterW said:

Both me and @Nickfromwales reckon those auto balancing manifold actuators will pay for themselves over and over

1

Do you have a link to this type of actuator?

[Nickfromwales]

33 minutes ago, Triassic said:

Do you have a link to this type of actuator?

yup

[Triassic]

I've read various rather complex posts on heating and hot water systems, I tend to be better able to understand a system when I have a diagram. Does anyone have a heating and DHW stem diagram that includes the use of a Sunamp?

Edited April 17, 2018 by Triassic

[Alexphd1]

@le-cerveau happy to see your figures we are very similar spec and also ended up with a 9KW ashp.

 

I am impressed with these auto balancing things! 

[Nickfromwales]

15 minutes ago, Triassic said:

I've read various rather complex posts on heating and hot water systems, I tend to be better able to understand a system when I have a diagram. Does anyone have a heating and DHW stem diagram that includes the use of a Sunamp?

Didn't someone email you a diagram a while ago? 

[Triassic]

Ahh you might be right, Ill do a search.

[Nickfromwales]

Just now, Triassic said:

Ahh you might be right, Ill do a search.

That one is specific to a customer so just use that to get your head around it   

[Triassic]

Found it thanks.

[Triassic]

@dogman kindly produced this diagram of his UFH heating system. I was wondering how much of this kit can be eliminated, thus saving money, by using a Sunamp  to do both DHW and UFH?

Edited April 17, 2018 by Triassic

[Nickfromwales]

4 hours ago, Triassic said:

@dogman kindly produced this diagram of his UFH heating system. I was wondering how much of this kit can be eliminated, thus saving money, by using a Sunampto do both DHW and UFH?

 

As it stands, with the PCM34 on ice due to technical problems, not that much TBH. See the last comment in my post here......

....where ive had to revert back to a buffer tank instead of a pair of 6kW PCM34 Sunamp units. 

As it says, im just juggling the anti-freeze isolation issue ( minimising the volume of antifreeze rich water by not having the buffer full of that water ) a bit more before I cement a design to overcome this problem. 

[oranjeboom]

31 minutes ago, Triassic said:

 I was wondering how much of this kit can be eliminated, thus saving money, by using a Sunamp  to do both DHW and UFH?

 

That's been on my mind also these past few days. Just been trawling 20+ pages on ebuild on sunamp discussions, but still none the wiser.  I suspect that with a Sunamp stack (having sufficient cells) could do both DHW and UFH, but would probably still need a combi if using PV or other heat source (for those Cumbrian weeks where you get no sun) or perhaps an ASHP....and then still need a buffer tank. But that plumber chap from the Valley's will be along soon enough no doubt with his wisdom.

[Alexphd1]

Is that diagram based for a system with ASHP cooling set up?

[Nickfromwales]

3 hours ago, oranjeboom said:

That's been on my mind also these past few days. Just been trawling 20+ pages on ebuild on sunamp discussions, but still none the wiser.  I suspect that with a Sunamp stack (having sufficient cells) could do both DHW and UFH, but would probably still need a combi if using PV or other heat source (for those Cumbrian weeks where you get no sun) or perhaps an ASHP....and then still need a buffer tank. But that plumber chap from the Valley's will be along soon enough no doubt with his wisdom.

Depends if you want cooling. 

If you don't, you could go all Sunamp for space heating and DHW via E10 grid electricity and fortify with PV where budget allows. 

[Triassic]

On 17/04/2018 at 17:21, Alexphd1 said:

Is that diagram based for a system with ASHP cooling set up?

I was wondering the same, maybe @Nickfromwales has the answer?