GSHP low temp plumbing and solid fuel

[optic]

I've spent the day working out my house heating plan but i'm not a plumber so though i would fish for ideas or just tell me the Bomb that i have just made ! 

Gshp size is not yet decided yet but 6 or 8 kw, Ground arrays are in. reading bits on the internet and to run the heating at 35 degrees then hi flow is the order of the day so based another project on the net with the amount of pipe in the 150mm concrete slab they had i cam up with the figures, but it's alot of pipe, been messing around with the layout of the valves etc and cam up this this but it still looks a bit messy to me.

http://imageshack.us/photo/my-images/36/heatingplan.jpg/

any comments welcome.

[optic]

that one might be better

[dhaslam]

There is quite a lot of pipe for the size of the heat pump.   It depends of course on how you use rooms but  the kitchen  could probably do with a lot less if it is mainly used for cooking.  Also the main living room might do with less and  the hall might do with just the leads to the other rooms.   On the other hand the bathrooms could do with more.   Bathrooms benefit from having the floors hot for a short period  in the morning and for this need more pipe.  Living rooms tend to have much more  passive heat  and also are heated more slowly over a long period.   

You have no  pipe length for the sunroom.    Presumably this will only be heated occasionally and will need to be heated quickly when needed.     My sun room has two  100 metre circuits, out of a total of  800 metres and takes a long time to heat up, about a full day.   I don't heat it regularly in the winter.    The kitchen circuit has never been used and the sitting room, where the stove is located doesn't need  heating, similarly the bedroom backing onto the stove,  so  only the main bedroom and two bathrooms are  heated regularly but only for a few hours in the morning and evening. Only about  250 metres of pipe and one  towel rail are heated and  that does absorb quite a lot of heat even at 35C.  In theory about 2 kW (6 watts per metre plus the towel rail) but in practice  a more like 3-4 kW.     

[optic]

Hi yes missed the sun room looking at three 100m pipes, only heated occasionally in winter weekends etc, the kitchen and living room will be used the most, the kitchen/dinner with sofa etc so used most for weekdays in winter maybe not even using the living room, half is an extension 6m x 3m velux and north facing windows so heat demand will be high, will have aga but not used much in the week,

can bump up the bathrooms could do 60m in the main bathroom and 18m on the ensuite, the living room is what i based my calcs on a low temp ufh system on the net had 4m x 4m room with 200m of pipe on a 3 inch centres, but that room is ssw facing with one well insulated outside wall so could drop the pipe length to two 75m loops ?

the hall and the bathrooms was going to leave as vent circuits, going to put stats on the bedrooms,

What heat pump do you have i'm still looking,

[ecogeorge]

Sorry , don't know what image shack runs on but it almost causes my mac to crash! soooooo long to load and even after zooming in eventually I cannot read the text -small and grey.
Don't believe you can have too much pipe in floor. It just dissipates the heat more quickly and if zoned areas then when up to heat it will turn off. Concentrate on getting the heat into the floor as quickly as possible.
To prevent  a yo yo effect of too cold too hot as room heats and cools try running water temp lower , -also improves efficiency.
Would recommend a buffer tank to reduce heat pump cycling (can also have other heat inputs to buffer -ie woodburner/pv dump / gas/ oil).
I run floors at 35c max , too hot really but I tend to fire woodburner too late in day and only put gshp on auto if very cold, -but I am a tight git.
rgds George
ps forgot to add have underfloor upstairs -only pipes clipped to underside of floor. Not convinced if it actually works ? but upstairs does not usually require heat. In our ensuite and bathroom I included a small radiator also but connected to same underfloor circuit. Seems to work well.
Secret is low temps and long run times for efficiency.My system has too many pumps -upstairs manifold has 1 x central heating pump, downstairs ditto. Woodburner uses central heating pump on differential thermostat and gshp has it's own circulation pump.
Will all be replaced by Willo A energy pumps in future.
pps
You must "zone " each area . Provide every zone (room) with its own thermostat -crazy not to. Don't listen to those who say adjust flow rates -just get the heat into the floors you need it as quickly as possible and then turn it off.
Nothing worse than trying to heat a cold room with a reduced flow (read reduced heat input) when she indoors is trying to watch strickly pratting about with a coat on.
just my 2p.

[titan]

The heat pump should be sized for the maximum  heat load and a matched ground array  so if your ( installed) array is for 6kW an 8kW unit would not be recommended, will it also be used for DHW  I looked at trying to combine heat sources but after a lot of research decided that for me anyway keeping them separate was more effective. So I have an UFH system that will heat the house and DHW (also with solar)  and a dry woodburner. I only have one pump no blender and no buffer tank but one section of UFH always open but that section is a zone with thermostatic control. Heating water with wood or coal is not cheap and takes heat from the stove for space heating, taking all the various losses within the holding, blending and distribution system and the power consumption of the extra pumps I doubt the overall energy efficiently or cost is better than a simpler system, although  not so much fun maybe. So much of this is also down to the design of the house for locating the various bits of the system and of course lifestyle, occupancy, number of occupants etc so no one answer.

[optic]

Hi this is not working without the picture,

try this one,
 

http://img198.imageshack.us/img198/3596/heatingplan3.jpg

[optic]

Thats Big, might have to save as and then open it with something that zooms, I did it in visio which image shack re sized but then the detail is lost and getting it to export to a jpg in a smaller size seems to throw up alot or errors,

Hi Titan the ground array is in it's two 50m slinkys 600m of pipe 2m depth in very heavy clay and some parts near pond in the ground water, i beleive this is good enough to support a 8 kw heat pump with DHW or a 10kw with just space heating, but i would rather run the smallest pump i can and oversizing the ground array would not be a problem,

want the the temp to be as low as seems george runs the same princable, thought the use of a manifold system would be too restrictive and the amount of connections needed it would cost alot more than just using 2 port valves for the isolation of different rooms, i.e heating the kitchen the heat pump would see 28mm pipes split into three 15mm 100m loops (plus the vent) which should be fine ? might need some balance valves on the small circuits.

Keeping the solid fuel out of the system would make it so much more simple but the stove in the living room that was install in our old 3 bed semi i think will over heat that room as it did in our old house 25 deegrees and just ticking over, leaving the doors open and it would keep the 80m2 house upto temperature but made drafts,

solid fuel is ineffiecent but have a free supply of wood and a 24 inch saw bench ! and i like the direct heat from a fire, the aga will make a trementious amount of heat it would be a waste not to be able to use some of it,


having trouble finding a heat pump supplier that does not cost the earth, i like the price of the navitron system and it but can it's controls do DHW ??   i've had some quotes but the last one the slinkys alone were over £500 more expensive than what i bought them for, and a two port manifold for the ground array for £470 plus Vat, if i have a system that is not MCS at a price i can afford then this would be ok but trying to find quotes that have not had the MCS price hike attached is looking hard,

[dhaslam]

want the the temp to be as low as seems george runs the same princable, thought the use of a manifold system would be too restrictive and the amount of connections needed it would cost alot more than just using 2 port valves for the isolation of different rooms, i.e heating the kitchen the heat pump would see 28mm pipes split into three 15mm 100m loops (plus the vent) which should be fine ? might need some balance valves on the small circuits.

Have you  checked all the details on doing this?   If you are running ordinary heating  pipe to the valves under the floor it will need to be protected  and where are the valves located?   Also you will need adapters to go  connect to the PEX pipe.    It would be a lot easier to use one  manifold downstairs and one upstairs. Keeping the system simple by using  the minimum number of 100 metre circuits means you could use standard eight or ten port manifolds and fewer valves.     The standard manifold valves are thermal (melting wax) and probably last better than  mechanical valves. The manifolds come with fittings for PEX.  The  manifolds should be matched to  wiring boxes that cut off the circulation pump when all the valves are closed.   

The thermal store needs to be fairly big because it  would be your main DHW store overnight and also if you  need to be able to run the heating on solid fuel only  it needs overnight storage as well.    Heat pumps are not very reliable.   If the price is reasonable you could consider  two small ones even though that doubles the chance of failure.   In mild weather you could run them alternatively on  their timers to utilize separate ground circuits. 

[optic]

The pipe is poly pipe under floor stuff, not sure on the 28mm yet but would be a tower runing loft to ground floor next to the hall which will have basically a corner or each room within reach.  i'll have another look at the manifolds,



Here are a couple of pictures to give some more idea, thousand words and all that,

[optic]

right see if this works









how does that look i'm stuck on explorer 6.0 which is really old so nothing looks good to me, the qulaity is there but you might need to save it and open them,

couple of questions will the central heating pumps prevent reverse flow through them or do they need check valves ? and will the mixing valves work ??

[Bodidly]

Hi optic

Great pics

That ground looks like clay so excellent conduction of energy to the ground loops.
 
I have only 200m of 32mm pipe in 1 horizontal loop and this successfully runs our 6kW GSHP (at a fairly low temperature) so your 600m in wet ground should be fine in a well insulated house. There is an interesting download on the John Cantor website that can help you get an idea about the relationship of the temperature of the underfloor heating and expected COP http://www.heatpumps.co.uk/heatpumpcalculator.html

This might also be worth a read through http://www.navitron.org.uk/forum/index.php/topic,15536.0.html

Beau