Will chemical cleaner get into the gravity DHW flow/return?

[Steelmasons]

If the pump is causing suction in the hw circuit, one way to dislodge things would be to close any isolator between the boiler and where it tees off between dhw and ch,turn off the boiler heat/electric, then run the pump on max (without the boiler) to circulate round the hw circuit. Then do your hammer tapping and cleaning out the filter etc.
Does it have a combined or separate feed/expansion pint on the hw pipework? If separate, The thing you have to watch is pulling in air through the expansion pipe or pumping over, you could always cap it *temporarily* while you're doing that pumping process.
However your cold water probably has more pressure and flow then your pump, so may be more effective if you can cobble that up.
Good luck!

Really??

With the boiler being the 'neutral' point then the circulator will be de-coupled from the gravity circuit....
Google 'hydronic'..

 

[John D v2.0]

Really??
Chaff from the wheat stand out like a sore thumb.
With the boiler being the 'neutral' point then the circulator will be de-coupled from the gravity circuit....
Google 'hydronic'..

Not sure why such a big chip on your shoulder, but I'll help you out with a bit of history further up the thread.

I notice when the HW only is on and both pipes are red hot (which does happen, eventually, just takes a long time) and I then put the CH on, both pipes immediately go cold, the pump must have created a bit of suction to pull it into the CH circuit.

 

[Steelmasons]

Not sure why such a big chip on your shoulder, but I'll help you out with a bit of history further up the thread.

"Both pipes immediately go cold"...more fool you for believing it.
The flow into the coil is partially block as I stated earlier , partially drain system and undo union @ cylinder coil (primary flow to cylinder) and clear blockage.
Job done.
BTW I have no chip on my shoulder although it ruffles my feathers when advice is given from others who haven't a clue.
You certainly don't have a clue , would you like me to enlighten you on some of your mis-guided posts?

 

[JohnD]

Not sure why such a big chip on your shoulder

Some of the old plumbers get a kick out of being rude and abusive.

 

[Steelmasons]

Some of the old plumbers get a kick out of being rude and abusive.

******* abuse deleted*********** Mod
Do you understand?

Pity you don't

 

[JohnD]

I bet that makes you feel big.

Get some of your buddies to tell you how great you are.

 

[Steelmasons]

I bet that makes you feel big.

Get some of your buddies to tell you how great you are.

I guess I'll ask them as my old man always used to say "lad, self praise is no praise"..thanks for the tip.

 

[John D v2.0]

"Both pipes immediately go cold"...more fool you for believing it.
The flow into the coil is partially block as I stated earlier , partially drain system and undo union @ cylinder coil (primary flow to cylinder) and clear blockage.
Job done.
BTW I have no chip on my shoulder although it ruffles my feathers when advice is given from others who haven't a clue.
You certainly don't have a clue , would you like me to enlighten you on some of your mis-guided posts?

I'm not sure why you disbelieve the op observation on his system, I didn't doubt him but maybe you can enlighten him on why he's wrong about it going cold.

Personally I always appreciate constructive advice, I would hope this forum is here to promote the knowledge of plumbing amongst anyone who is interested! I certainly don't claim to know everything, as with most people I hope to learn more.
I certainly wouldn't suggest anything that could cause a danger unless I was 100% sure, but in terms of suggestions since the op asked I hope he appreciates it.
If he doesn't want to take my suggestion that's also fine.

 

[John D v2.0]

I guess I'll ask them as my old man always used to say "lad, self praise is no praise"..thanks for the tip.

was his other advice "if you meet someone who knows less than you about something, don't try to help, just give them as much abuse as possible"

 

[Steelmasons]

I will always help where I can , what I won't do is help these armchair googlers who portray themselves as knowing what their talking about.

 

[John D v2.0]

Are you a qualified time served plumbing a heating engineer with papers/certs?
I happen to be which is the reason I have this gift of being able to decipher the chaff from wheat.

Well glad you're proud to be a little man. I never claimed to be more than I am. Bye

 

[AGAS]

Some of the old plumbers get a kick out of being rude and abusive.

there you go again as i mentioned in other thread , you know what your trying to do but mods will see through that hopefully

Well glad you're proud to be a little man. I never claimed to be more than I am. Bye

whats up , getting a little hot there . you are trying to sound that you know what what your talking about but not accepting that you could be a more informed and you showing your inexperience ( or non ) but instead calling it rude or abusive , learn from it and move on and grow up