dual fuel central heating correct setup

airliebeach · 16-09-2019 11:34am #1

I've just had a new oil fired boiler installed.
Have an open fire back boiler.
I'm trying to figure out how its all connected?
As in, the 2 circulating pumps pumping in same direction or against?
Is the non return valve on oil burner because the 2 pumps are pumping against each other?
Should I have non return valve on back boiler also?
Apparently there's a safety issue if power goes and pump stops, heat must be dispersed, some people suggest direct uninhibited line to cylinder, i think i have pipe straight up to expansion tank, Would this be typical?
any feedback would be appreciated.

16-09-2019 12:01pm

There are devices that plumbers use like heat genies/system links etc... to connect two heat sources in a safe manor, I have seen more than one heating system destroyed by getting things wrong.

Dtp1979 · 16-09-2019 11:00pm

airliebeach wrote: »

I've just had a new oil fired boiler installed.
Have an open fire back boiler.
I'm trying to figure out how its all connected?
As in, the 2 circulating pumps pumping in same direction or against?
Is the non return valve on oil burner because the 2 pumps are pumping against each other?
Should I have non return valve on back boiler also?
Apparently there's a safety issue if power goes and pump stops, heat must be dispersed, some people suggest direct uninhibited line to cylinder, i think i have pipe straight up to expansion tank, Would this be typical?
any feedback would be appreciated.

Post a pic of the entire layout of the hotpress and we’ll see if it’s right

antix80 · 16-09-2019 11:03pm

I remember my dad's house.. If the central heating was on and you turned on the immersion, water started chugging out of the tank and down the stairs... I lived in fear of it.

airliebeach · 14-12-2019 1:36pm

Dtp1979 wrote: »

Post a pic of the entire layout of the hotpress and we’ll see if it’s right

Hello, finally getting back to this.
Attached is my basic setup diagram.
Not sure how back boiler and oil boiler are interconnected?

All I know is oil boiler heats the rad from one side, the back boiler heats it from the other side. That is the flow and return seem to be reversed.
Is that correct?
Can someone post a pic of how they should be interconnected?
Also, what is the pipe on the return of the backboiler, going up to the attic and just closed off up there, for?

airliebeach · 14-12-2019 1:40pm

Dtp1979 wrote: »

Post a pic of the entire layout of the hotpress and we’ll see if it’s right

Hello, finally getting back to this.
Attached is my basic setup diagram.
Not sure how back boiler and oil boiler are interconnected?

All I know is oil boiler heats the rad from one side, the back boiler heats it from the other side. That is the flow and return seem to be reversed.
Is that correct?
Can someone post a pic of how they should be interconnected?
Also, what is the pipe on the return of the backboiler, going up to the attic and just closed off up there, for?

BDI · 14-12-2019 1:49pm

Are you using your back boiler to heat your house with question marks?

It’s open vented and non return valves seem in order. Is there some sort of switch that stops the oil boiler firing if the back boiler pump is running?

Dtp1979 · 14-12-2019 2:09pm

airliebeach wrote: »

Hello, finally getting back to this.
Attached is my basic setup diagram.
Not sure how back boiler and oil boiler are interconnected?

All I know is oil boiler heats the rad from one side, the back boiler heats it from the other side. That is the flow and return seem to be reversed.
Is that correct?
Can someone post a pic of how they should be interconnected?
Also, what is the pipe on the return of the backboiler, going up to the attic and just closed off up there, for?

The non return valves are most certainly not right. There’s a lot wrong with that drawing.

BDI · 14-12-2019 2:12pm

Dtp1979 wrote: »

The non return valves are most certainly not right. There’s a lot wrong with that drawing.

Typical boards post. What is wrong with the drawing? Apart from the return arrows on the boiler going backwards but I’m guessing that’s a mistake.

airliebeach · 14-12-2019 2:35pm

BDI wrote: »

Are you using your back boiler to heat your house with question marks?

It’s open vented and non return valves seem in order. Is there some sort of switch that stops the oil boiler firing if the back boiler pump is running?

Good few ? At the moment alright.
Yes it's supposed to heat the house.
AFAI there is no switch to stop the back boiler like that.

airliebeach · 14-12-2019 2:37pm

Dtp1979 wrote: »

The non return valves are most certainly not right. There’s a lot wrong with that drawing.

What's wrong with non return valves?
Can you tell me what else looks wrong so I can figure it out?
Thanks.

airliebeach · 14-12-2019 2:39pm

BDI wrote: »

Typical boards post. What is wrong with the drawing? Apart from the return arrows on the boiler going backwards but I’m guessing that’s a mistake.

Thanks but shouldn't the return direction be back into the boiler and the flow out of the boiler?

BDI · 14-12-2019 2:39pm

airliebeach wrote: »

Thanks but shouldn't the return direction be back into the boiler and the flow out of the boiler?

Haha sorry I was looking at it upside down

airliebeach · 14-12-2019 2:44pm

My main problem is that the oil boiler cuts out after a few minutes. So I'm guessing the heated water is not being moved around system for some reason.
Any suggestions why this might be?

While investigating, I noticed that one of the rads is heated from one side with oil boiler and the other side from back boiler... Weird right?

BDI · 14-12-2019 2:58pm

airliebeach wrote: »

My main problem is that the oil boiler cuts out after a few minutes. So I'm guessing the heated water is not being moved around system for some reason.
Any suggestions why this might be?

While investigating, I noticed that one of the rads is heated from one side with oil boiler and the other side from back boiler... Weird right?

If that rad is being heated by the flow from both boilers it won’t heat all that much.

airliebeach · 14-12-2019 3:06pm

BDI wrote: »

If that rad is being heated by the flow from both boilers it won’t heat all that much.

Exactly, when both are running, there must be a conflict...

Dtp1979 · 14-12-2019 9:38pm

BDI wrote: »

Typical boards post. What is wrong with the drawing? Apart from the return arrows on the boiler going backwards but I’m guessing that’s a mistake.

Ok genius, seeing it at a 2 second glance I can see there is no gravity circuit. There’s a non return valve Beside the back boiler, making the back boiler essentially a bomb, and it’s a combined feed and expansion setup too. All wrong. Now, that’s only 2 seconds. If I get a chance I’ll take a proper look.

jimf · 14-12-2019 10:03pm

airliebeach wrote: »

My main problem is that the oil boiler cuts out after a few minutes. So I'm guessing the heated water is not being moved around system for some reason.
Any suggestions why this might be?

While investigating, I noticed that one of the rads is heated from one side with oil boiler and the other side from back boiler... Weird right?

is this from cold with no back boiler running

jimf · 14-12-2019 10:18pm

BDI wrote: »

Typical boards post. What is wrong with the drawing? Apart from the return arrows on the boiler going backwards but I’m guessing that’s a mistake.

can you elaborate please on what a typical boards post is

a lot of us on here give of our time freely to help others with our maybe limited knowledge

most of the time we get positive reports back

hopefully your opinion is yours only

BDI · 14-12-2019 11:27pm

jimf wrote: »

can you elaborate please on what a typical boards post is

a lot of us on here give of our time freely to help others with our maybe limited knowledge

most of the time we get positive reports back

hopefully your opinion is yours only

It would be typical that somebody comes along and says something is wrong but doesn’t bother to say why.

BDI · 14-12-2019 11:36pm

Dtp1979 wrote: »

Ok genius, seeing it at a 2 second glance I can see there is no gravity circuit. There’s a non return valve Beside the back boiler, making the back boiler essentially a bomb, and it’s a combined feed and expansion setup too. All wrong. Now, that’s only 2 seconds. If I get a chance I’ll take a proper look.

The feed and expansion tank come off the flow side of the back boiler. I would say having a non return valve on the return side would not make it any less of a bomb than before. Ok I agree we could take the feed tank into the return between the non return valve and the boiler return but that’s why we are here, to share knowledge.

jimf · 14-12-2019 11:36pm

the typical ans to anybody with a combined heating system that incorporates a back boiler would be to get a professional that knows and understands how the 2 can be combined to work safely

a back boiler not installed properly without an unobstructed gravity circuit is not something you mess with

Dtp1979 · 15-12-2019 1:06pm

BDI wrote: »

The feed and expansion tank come off the flow side of the back boiler. I would say having a non return valve on the return side would not make it any less of a bomb than before. Ok I agree we could take the feed tank into the return between the non return valve and the boiler return but that’s why we are here, to share knowledge.

I think you’d be best off not sharing your lack of knowledge on here. Someone in the future might read your advice and think it’s ok to do what you suggested.

BDI · 15-12-2019 1:12pm

Dtp1979 wrote: »

I think you’d be best off not sharing your lack of knowledge on here. Someone in the future might read your advice and think it’s ok to do what you suggested.

I openly admit I’ve little experience with back boilers. You seem to just want to call people’s lack of experience out to show your superiority instead offering the op advise on how not to blow himself up.

Why post on this forum if not to share your knowledge?

Dtp1979 · 15-12-2019 1:19pm

BDI wrote: »

I openly admit I’ve little experience with back boilers. You seem to just want to call people’s lack of experience out to show your superiority input offering the op advise on how not to blow himself up.

Why post on this forum if not to share your knowledge?

If you’ve little experience with back Boilers then don’t be offering dangerous advice. You’re the one who questioned my knowledge by claiming there was nothing wrong with the drawing when I said there was plenty wrong. I have no notions of superiority but I’ll always shut down dangerous advice when I see it simply because somebody reading it in future might actually read it and put it in to practice.
I said clearly a few posts ago that when I get a chance I’ll take a proper look at the drawing and that’s when I’ll offer advice.

Dtp1979 · 15-12-2019 1:27pm

airliebeach wrote: »

Hello, finally getting back to this.
Attached is my basic setup diagram.
Not sure how back boiler and oil boiler are interconnected?

All I know is oil boiler heats the rad from one side, the back boiler heats it from the other side. That is the flow and return seem to be reversed.
Is that correct?
Can someone post a pic of how they should be interconnected?
Also, what is the pipe on the return of the backboiler, going up to the attic and just closed off up there, for?

-Ok op, getting back to this now. The blue line going to the attic from the pump, what’s happening there, it seems to terminate in the open attic?

- combined feed and vent in the attic is incorrect.

- there should be absolutely no non return valve on the primary circuit. Especially where it is!

-there’s no gravity circuit from the back boiler to the cylinder.

- there should be a dual coil cylinder installed but this isn’t absolutely necessary once the solid fuel is piped correctly to the cylinder. Using a single coil just means that the oil heating won’t heat the domestic hot water.

There’s also a valve on the coil return. That’s an absolute no no.

Long story short op, you need a professional to sort this out. It’s not a diy job.

BDI · 15-12-2019 1:27pm

Dtp1979 wrote: »

If you’ve little experience with back Boilers then don’t be offering dangerous advice. You’re the one who questioned my knowledge by claiming there was nothing wrong with the drawing when I said there was plenty wrong. I have no notions of superiority but I’ll always shut down dangerous advice when I see it simply because somebody reading it in future might actually read it and put it in to practice.
I said clearly a few posts ago that when I get a chance I’ll take a proper look at the drawing and that’s when I’ll offer advice.

I never questioned your advice I asked you to elaborate.

Dtp1979 · 15-12-2019 1:31pm

BDI wrote: »

Typical boards post. What is wrong with the drawing? Apart from the return arrows on the boiler going backwards but I’m guessing that’s a mistake.

Judging by the tone of your post and stating that only the arrows were wrong, then yes, you were questioning my knowledge.

BDI · 15-12-2019 1:38pm

Dtp1979 wrote: »

Judging by the tone of your post and stating that only the arrows were wrong, then yes, you were questioning my knowledge.

Surely you could have drew a picture by now instead of trying to have an internet fight with me, do you want me to draw my picture? Of what I’d do?

Dtp1979 · 15-12-2019 1:50pm

BDI wrote: »

Surely you could have drew a picture by now instead of trying to have an internet fight with me, do you want me to draw my picture? Of what I’d do?

Seeing as you think the nrv is grand I’d say no. I’m sure you could google correct way to do it and look all clever. The op is not a plumber and I’m not going to show a diyer(no offence op) how to attempt such a project

15-12-2019 1:51pm

BDI wrote: »

Surely you could have drew a picture by now instead of trying to have an internet fight with me, do you want me to draw my picture? Of what I’d do?

Why don’t you.

Also if you could stay away from winding up other posters that would be nice.

Wearb · 15-12-2019 1:53pm

BDI wrote: »

Typical boards post. What is wrong with the drawing? Apart from the return arrows on the boiler going backwards but I’m guessing that’s a mistake.

MOD NOTE: If you don't stop dragging this thread off topic I will infract you for this post where you were clearly trolling. So either stop posting on this thread or be very careful to stick to the topic.

BDI · 15-12-2019 2:19pm

I’d go with that myself. And I’m leaving this thread good luck lads.

Dtp1979 · 15-12-2019 2:23pm

BDI wrote: »

I’d go with that myself. And I’m leaving this thread good luck lads.

Good luck with that. It won’t work, but good luck.

Dtp1979 · 15-12-2019 2:47pm

BDI wrote: »

I’d go with that myself. And I’m leaving this thread good luck lads.

You have the oil return joined into the gravity side of the back boiler. You’ve the oil flow teed into the bb gravity circuit. And when the oil is on it’s gonna heat the back boiler.

airliebeach · 15-12-2019 10:03pm

So, further investigation reveals oil boiler's circulating pump extremely hot.
And help would be great.
It's a 2 month old pump...

Dtp1979 · 15-12-2019 10:32pm

airliebeach wrote: »

So, further investigation reveals oil boiler's circulating pump extremely hot.
And help would be great.
It's a 2 month old pump...

What do you need to know? I’ve already explained that the system is piped arseways. You really need a good plumber in there. There’s no quick fix. The one bit of advice I’d give, and urge, is not to light the back boiler until it’s fixed.

airliebeach · 15-12-2019 11:52pm

Dtp1979 wrote: »

What do you need to know? I’ve already explained that the system is piped arseways. You really need a good plumber in there. There’s no quick fix. The one bit of advice I’d give, and urge, is not to light the back boiler until it’s fixed.

Thanks Dtp for all the info.
Will have proper look at what you said tomorrow evening and will prob come back with more questions.
For now though, the drawing is accurate, just the setup in the house seems pretty crap based on your feedback. I def won't be attacking the issues you raised, myself, but I'd like to fix the immediate problem of the oil burner switching off. Baring in mind it's been working without a hitch for last 2 months...
Have you any ideas why the pump is red hot? Generally these should be warm but not scaldy right?

jimf · 15-12-2019 11:57pm

airliebeach wrote: »

Thanks Dtp for all the info.
Will have proper look at what you said tomorrow evening and will prob come back with more questions.
For now though, the drawing is accurate, just the setup in the house seems pretty crap based on your feedback. I def won't be attacking the issues you raised, myself, but I'd like to fix the immediate problem of the oil burner switching off. Baring in mind it's been working without a hitch for last 2 months...
Have you any ideas why the pump is red hot? Generally these should be warm but not scaldy right?

its quite possible the pump has failed

system could be low in water

your boiler is cutting out so fast because the stat is doing its job for whatever reason there is no water circulating through the boiler

airliebeach · 15-12-2019 11:57pm

Dtp1979 wrote: »

Ok genius, seeing it at a 2 second glance I can see there is no gravity circuit. There’s a non return valve Beside the back boiler, making the back boiler essentially a bomb, and it’s a combined feed and expansion setup too. All wrong. Now, that’s only 2 seconds. If I get a chance I’ll take a proper look.

Yeah the feed/expansion combo looked wrong even to my ignorant eye. But unfortunately that's actually the way it is. Where should the feed be connected?

airliebeach · 15-12-2019 11:59pm

jimf wrote: »

is this from cold with no back boiler running

Yep.
Also if backboiler is running at same time, oil boiler will still cut out after a while

airliebeach · 16-12-2019 12:01am

BDI wrote: »

The feed and expansion tank come off the flow side of the back boiler. I would say having a non return valve on the return side would not make it any less of a bomb than before. Ok I agree we could take the feed tank into the return between the non return valve and the boiler return but that’s why we are here, to share knowledge.

Why is it bomb-like?
It has unobstructed route to expansion tank...

airliebeach · 16-12-2019 12:04am

jimf wrote: »

the typical ans to anybody with a combined heating system that incorporates a back boiler would be to get a professional that knows and understands how the 2 can be combined to work safely

a back boiler not installed properly without an unobstructed gravity circuit is not something you mess with

I realise a pro would be best. But this system is already in place and I'm just trying to figure it out to fix my immediate problem.
Can you explain exactly what is a gravity circuit please?

airliebeach · 16-12-2019 12:13am

Dtp1979 wrote: »

-Ok op, getting back to this now. The blue line going to the attic from the pump, what’s happening there, it seems to terminate in the open attic?

- combined feed and vent in the attic is incorrect.

- there should be absolutely no non return valve on the primary circuit. Especially where it is!

-there’s no gravity circuit from the back boiler to the cylinder.

- there should be a dual coil cylinder installed but this isn’t absolutely necessary once the solid fuel is piped correctly to the cylinder. Using a single coil just means that the oil heating won’t heat the domestic hot water.

There’s also a valve on the coil return. That’s an absolute no no.

Long story short op, you need a professional to sort this out. It’s not a diy job.

Thanks for this post.
Yep just terminates in the attic. What was it intended for. Its a smaller pipe. Possibly for the feed?

Combined feed and vent always a bad idea? Or just poorly done here?

No non return valve? What do you mean exactly by primary circuit? (stupid question I know). What harm is a non return valve as long as its fitted in correct direction? Where should it be?

What is the gravity circuit? Maybe I have this. But if pipe disappears under ground then my knowledge goes with it...

I've a single coil. Both boilers connected to it.

airliebeach · 16-12-2019 12:22am

jimf wrote: »

its quite possible the pump has failed

system could be low in water

your boiler is cutting out so fast because the stat is doing its job for whatever reason there is no water circulating through the boiler

Think you could be right about pump Jim. Although it is rotating. Not sure of internal makeup of pump but maybe fins broke or something. But sounds OK!!

jimf · 16-12-2019 12:32am

airliebeach wrote: »

Think you could be right about pump Jim. Although it is rotating. Not sure of internal makeup of pump but maybe fins broke or something. But sounds OK!!

if this pump was only fitted 2 months ago get the installer back

John.G · 04-03-2020 10:29pm

BDI wrote: »

Surely you could have drew a picture by now instead of trying to have an internet fight with me, do you want me to draw my picture? Of what I’d do?

A little late but came across this some time ago, it may be of some help.

dual fuel central heating correct setup

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