Gravity flow and return from wood burning stove to thermal store ??

[Crowbar259]

Hi i would like some other plumbers advice who have had good experience with solid fuel and gravity installations. I have just fitted a 300 litre thermal store in a customers new house. The thermal store is upstairs in the hot press and the wood burner downstairs. This house however has concrete floors upstairs so when i was first fixing my 28mm flow and return up the chimney breast and onto first floor i had only a limited amount of a rise i could get on the flow and return as the depth on the finished screed floor was only 3.5 inches and the length of run from point at when they projected up onto first floor and ran horizontally to the the thermal store was 12 metres . The wood burner has not been installed yet but my only concern before it is installed and lit is that will the long length of horizontal run to the store be sufficient enough for the heat this 20kw wood burner is producing to circulate fast enough via only gravity circulation ??
I mentioned this concern to my plumbing suppliers and they said some of their other plumbers are fitting a pump on the primary f/r from the stove just to move the hot water more quicker but still piping via gravity circulation just incase of power failure and safety . Would this be recommend by anybody ? And if not why ?

 

[Ermintrude]

You should call HETAS and check they are qualified also building control. Sound like utter idiots. So pipes come out of stove then go down into a screed then up...... Not really going to convect . Screed will zap all the heat too. Pump will kill any gravity also. Thermal store 300l for 20kw? Probably 1/2 the size it should be.

Do not pay them any money. Until your happy. Sound just like an idiot near me. Removes gas appliances and isn't GSR and hasn't got a clue but he's throwing stoves in all over. Reported him to gas safe about a dozen times and they just sent him a letter. Asks for help all the time. Hope your not imminent victim of a soli cowboy!

 

[Dotty]

Crowbar's the one doing the job Ermi.....

Would recommend you contact HETAS for advice and see what they say.

And which merchants was it? Bassetts? Beggs? Jebs?

 

[Ermintrude]

Ha ha ha. Didn't read it properly due to toddler cornflake madness! But I can sadly conclude that mr crowbar you are a twonk!

Well done for asking, shame on you for winging it! Go back say sorry rip it all out and get a pro in not some plonker who gives u half-baked advise. I am very guarded about telling other lads over the phone about what to do and how to do a job. They are doing my work and using my noggin and not paying..... Jog on!

 

[Best]

12 metres is a very long distance to travel horizontally with gravity pipes!
This is a typical example of a new house not having the solid fuel boiler position & piping arrangement sorted at the design stage of the house.
"let's stick a solid fuel fire in that room". :smile:

 

[Killy Bing]

12metres?

ill ignore the gravity issue and leave that to the others !!!

12metres is a long run when it comes to thermal expansion. Expect joints to pop and leak often !!!

that store needs moving....

 

[SimonG]

Dont listen to your merchant for installation advice. I turned up to swap an electric shower. Old one 8.5 new one 9.5. But the bloke in the merchants sais it would be ok. Well had he seen the cable size, had he seen the fuse size, no.

In instances when you are lacking the knowledge or experience you need to pass or bring somebody in to work with who has the experience.

 

[lame plumber]

nuff said 🙂

 

[Crowbar259]

I think some people are getting mixed up in my description of this job. The 28mm primary f/r rise vertically off the stove straight up onto the upstairs sub floor ( concrete floors upstairs ) they then travel horizontally under the floor for 12 metres to the store. The pipes from the stove to the store have a rise the whole way as i pecked the pipes up with wood on the horizontal run under the floor.
I have piped grant triple pass back boilers many times before on gravity but had no issue with this as the houses were small and hotpress always a short run from boiler. I know how a gravity system works but just unsure how far i can get away with a long run like this and such a high output stove.
But as best says above , us plumbers go to a new build and the customer just decides at the last minute oh by the way i forgot to mention i want to stick a stove with boiler in that room .