diff --git a/defaults/main.yml b/defaults/main.yml
index 155b3fa..054a890 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -165,6 +165,10 @@ heat_watch_server_url: "{{ heat_watch_server_uri }}"
 # heat_engine_workers: 4
 # heat_api_workers: 4
 
+## Cap the maximum number of threads / workers when a user value is unspecified.
+heat_api_threads_max: 16
+heat_api_threads: "{{ [[ansible_processor_vcpus|default(2) // 2, 1] | max, heat_api_threads_max] | min }}"
+
 heat_service_in_ldap: false
 
 ## Plugin dirs
diff --git a/releasenotes/notes/capping_heat_workers-13791c456e59277d.yaml b/releasenotes/notes/capping_heat_workers-13791c456e59277d.yaml
new file mode 100644
index 0000000..eae7447
--- /dev/null
+++ b/releasenotes/notes/capping_heat_workers-13791c456e59277d.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - Capping the default value for the variables
+    ``heat_api_workers`` and ``heat_engine_workers`` to 16 when the user
+    doesn't configure these variables. Default value is half the number of
+    vCPUs available on the machine with a capping value of 16.
diff --git a/templates/heat.conf.j2 b/templates/heat.conf.j2
index b4a0d78..d5316e6 100644
--- a/templates/heat.conf.j2
+++ b/templates/heat.conf.j2
@@ -1,8 +1,5 @@
 # {{ ansible_managed }}
 
-{% set _api_threads = ansible_processor_vcpus|default(2) // 2 %}
-{% set api_threads = _api_threads if _api_threads > 0 else 1 %}
-
 [DEFAULT]
 # Disable stderr logging
 use_stderr = False
@@ -24,7 +21,7 @@ trusts_delegated_roles = {{ heat_trusts_delegated_roles | join(',') }}
 
 auth_encryption_key = {{ heat_auth_encryption_key }}
 
-num_engine_workers = {{ heat_engine_workers | default(api_threads) }}
+num_engine_workers = {{ heat_engine_workers | default(heat_api_threads) }}
 
 ## RPC Backend
 rpc_backend = {{ heat_rpc_backend }}
@@ -55,7 +52,7 @@ auth_uri = {{ keystone_service_internalurl }}
 
 [heat_api]
 bind_port = {{ heat_service_port }}
-workers = {{ heat_api_workers | default(api_threads) }}
+workers = {{ heat_api_workers | default(heat_api_threads) }}
 
 [heat_api_cfn]
 bind_port = {{ heat_cfn_service_port }}