Search the forum,

Gravity DHW with conventional oil boiler with 1 flow & 1 return top connections?

Discuss Gravity DHW with conventional oil boiler with 1 flow & 1 return top connections? in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Status
Not open for further replies.
B

bigjr

For the last 30 years our house has been very successfully heated by a 70/90 Myson oil fired cased boiler in the kitchen. 1 flow + 1 return on one side for gravity DHW system and 1 flow + 1 return on the other side for pumped radiator circuit. My heating engineer advised that the boiler should be changed for greater effeciency. Unfortunately a condensing oil boiler was not an option due to difficulties in installing a suitable flue. Therefore he installed a new conventional oil boiler of the same output capacity. This new boiler has just 1 flow and 1 return connections on the top facing upwards. The heating engineer has fitted the branch of a 28mm tee to each of these connections and joined one side of the tees to the gravity DHW and the other side to the pumped radiator circuit.
The gravity DHW circuit is not heating the hot water in the cylinder to anywhere near the previous temperature, presumably because the pumped radiator circuit is drawing all the water from the boiler flow tee. My heating engineer seems to be uncertain as to the best way to cure the problem and is talking about experimenting with different modifications to see if anything works.!!!! I would be interested to learn if a new conventional boiler with 2 top connections can ever be plumbed successfully into a gravity DHW system originally designed for a boiler with 4 side connections? What is the most practical way to reconfigure the system?
 
I work with gas not oil ... however Id believe the only difference will be the fuel used to heat regards design? If there's only two tappings then I'd assume it was designed for a fully pumped system design rather than gravity. The problem with what you're describing is that there's a chance that the pump can reverse the circulation on the cylinder and actually 'suck' heat out of the cylinder via the pipework if cold water from the radiators is pumped around them!
 
He could alter the return to incorporate an injection tee.this uses the pump to assist the gravity hot water.
 

Attachments

  • image.jpg
    image.jpg
    13.3 KB · Views: 39
i;ve seen this set up work successfully on a gas boiler, although it's not ideal, it did work alright
i'm not sure where the pump was fitted though
and as said above, using an injector tee might help.
 
Shouldnt have left the water on gravity. Also with the amount of options available for flueing a condensing boiler it sounds like its been done on the cheap.
 
He has done it wrong & sounds like he hadn't a clue.
Fully pumped with separate hot water circuit & the system changed to a sealed system if it is able to take the extra pressure & has no leaks.
 
Best said:
He has done it wrong & sounds like he hadn't a clue.
Fully pumped with separate hot water circuit & the system changed to a sealed system if it is able to take the extra pressure & has no leaks.
Click to expand...
He didn say it was a sealed system.
it has obviously been done n the cheap. Now looking for cheap answers. It should have been converted to fully pumped and a condensing boiler. If it has a normal oil boiler there is definitely a replacement condensing that would have fitted.


but he now has a problem that needs a simple fix.

Injector tee is an old fix but should work and be cheap to install.
 
obviously fully pumped is the way to go here, but i'll bet you could get the hw to work on gravity
i reckon a swept tee on the flow would do the job

to the op, what was the distance between the boiler and hw cylinder ?
 
SE boilers always have 4 tappings anyway. Well the ones ive seen have :)
 
Injector tee's still quite common on solid fuel / log / wood back boilers.
 
Chalked said:
Injector tee is an old fix but should work and be cheap to install.
Click to expand...

Def agree, - injector tee is the cheapest, easiest way for to get the hot water heating better & won't cause pump over. I have used them on solid fuel boilers. Still going to be a slow way to heat the water with an oil boiler & gravity only hot water will also remain slow.
 
Best said:
Def agree, - injector tee is the cheapest, easiest way for to get the hot water heating better & won't cause pump over. I have used them on solid fuel boilers. Still going to be a slow way to heat the water with an oil boiler & gravity only hot water will also remain slow.
Click to expand...

Thank you all for your suggestions. With hindsight the job has probably been done on the cheap. House is a holiday home in the west of Ireland where good heating engineers are like hen's teeth and building regs aren't always followed. The existing boiler had a flue going up a lined chimney in the centre of the house (no where near any outside walls) - hence the problem with a flue suitable for a condensing boiler. The SE boiler was specially made by Warmflow and only when it was delivered did the plumber realize it had only 2 top tappings instead of the normal 2 right and 2 left tappings of older SE boilers.

Will try an injector tee on the return and a sweep tee on the flow as suggested.

Thank you again everyone for your opinions.
 
You got bad advice regarding the boiler. Grant and other manufacturers do a flue liner for condensing boilers.
 

Attachments

  • image.jpg
    image.jpg
    45.9 KB · Views: 10
Status
Not open for further replies.

Reply to Gravity DHW with conventional oil boiler with 1 flow & 1 return top connections? in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Similar plumbing topics

johndave
Outdoor stopcock doesn't fully close
Hi all I'm hoping someone can shine a light on this for me Since our stop tap on the pavement has now been filled with sand for whatever reason, we are relying on our property fitted stopcock (this is outside on our garage wall) Unfortunately turning this to the closed position only reduces...
Replies
3
Views
230
exedon2
exedon2
Creating content since 2001. Untold Media.

Newest Plumbing Threads

Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock